fix(bitcoin): stop writing a datadir bitcoin.conf that conflicts with -conf=/tmp/rpc.conf

Since a597c1d9 (bitcoind RPC creds off argv), bitcoin-core and bitcoin-knots
launch bitcoind with -conf=/tmp/rpc.conf and pass all other settings as CLI
args; bitcoind never reads /var/lib/archipelago/bitcoin/bitcoin.conf again.

write_bitcoin_conf, ensure_bitcoin_rpc_config, and bootstrap's
run_bitcoin_rpc_repair were never updated to match — they kept writing/
"repairing" server=/rpcbind=/rpcallowip=/listen= into that datadir file on
every install, reinstall, and service restart. Bitcoin Core's own
datadir-conflict safety check then refuses to start whenever that file
exists alongside an explicit -conf= arg, so the write and every repair
of it directly caused the crash it was trying to prevent.

Also drop the "restart already-running container after bitcoin.conf
repair" adoption-path branch: it assumed bind settings live in that file
and needs a restart to pick them up, which hasn't been true since
a597c1d9 — the running container's CLI args are already correct.

Replaces both writers with remove_stale_bitcoin_conf(), which renames
(not deletes) any leftover file so already-affected nodes self-heal on
next install/restart instead of staying permanently broken.

bitcoin_data_volume_gb is removed as dead code (it only fed the deleted
prune= line in write_bitcoin_conf, itself unused since a597c1d9 hardcoded
-prune=550 in the manifest's small-disk branch).

Investigated after a crash loop on archy-x250-beta; full incident
timeline and patch rationale in bitcoin-conf-crash-patch.md.

core/archipelago/src/bootstrap.rs

@@ -154,9 +154,9 @@ pub async fn ensure_doctor_installed() {
     }
     match run_bitcoin_rpc_repair().await {
         Ok(true) => {
-            info!("Repaired Bitcoin RPC bind settings; running Bitcoin containers left untouched")
+            info!("Removed stale bitcoin.conf; running Bitcoin containers left untouched")
         }
-        Ok(false) => debug!("Bitcoin RPC bind settings already usable"),
+        Ok(false) => debug!("No stale bitcoin.conf found"),
         Err(e) => warn!("Bitcoin RPC repair failed (non-fatal): {:#}", e),
     }
     match run_apps_dir_repair().await {
@@ -577,52 +577,30 @@ exit 2
 }
 
 async fn run_bitcoin_rpc_repair() -> Result<bool> {
-    // Older installs can have a container-owned bitcoin.conf with only rpcauth
-    // and printtoconsole. Repair it at startup so OTA fixes existing nodes
-    // without a manual uninstall/reinstall. Bind/port stay in the container
-    // command line to avoid duplicate RPC endpoint definitions.
+    // bitcoind is launched with -conf=/tmp/rpc.conf and never reads a
+    // datadir bitcoin.conf (apps/bitcoin-core & bitcoin-knots manifest.yml,
+    // commit a597c1d9 — bind/port live only on the container command line).
+    // A leftover file from an older install makes Bitcoin Core's own
+    // datadir-conflict safety check refuse to start on every subsequent
+    // start. Remove it instead of "repairing" it into existence — this
+    // previously wrote server=/rpcbind=/rpcallowip=/listen= into the file,
+    // which is exactly what caused the conflict.
     let script = r#"
 set -eu
 conf=/var/lib/archipelago/bitcoin/bitcoin.conf
 [ -f "$conf" ] || exit 0
-changed=0
-ensure_line() {
-    line="$1"
-    key="${line%%=*}"
-    if ! grep -q "^${key}=" "$conf"; then
-        printf '%s\n' "$line" >> "$conf"
-        changed=1
-    fi
-}
-ensure_line server=1
-# rpcbind=0.0.0.0 is required inside the container: with rpcallowip set but
-# no rpcbind, bitcoind binds RPC to the container's loopback only and every
-# dial over the container network (LND, bitcoin-ui) is refused — the fresh-
-# install "LND took 5 attempts" / bitcoin-rpc 502 failure (host publish stays
-# 127.0.0.1-only, so exposure is unchanged).
-ensure_line rpcbind=0.0.0.0
-ensure_line rpcallowip=0.0.0.0/0
-ensure_line listen=1
-# Log-volume fix: printtoconsole=1 duplicated every log line (incl. per-block
-# IBD "UpdateTip" spam) into journald via conmon on top of the datadir
-# debug.log bitcoind already writes. Console off; debug.log stays (bitcoind
-# self-shrinks it on restart).
-if grep -q '^printtoconsole=1' "$conf"; then
-    sed -i 's/^printtoconsole=1$/printtoconsole=0/' "$conf"
-    changed=1
-fi
-[ "$changed" -eq 0 ] && exit 0
+mv "$conf" "$conf.disabled-$(date +%s)"
 exit 2
 "#;
     let status = host_sudo(&["sh", "-lc", script])
         .await
-        .context("repair bitcoin.conf RPC bind settings")?;
+        .context("remove stale bitcoin.conf RPC bind settings")?;
     match status.code() {
         Some(0) => Ok(false),
         // Do not restart Bitcoin from bootstrap. During IBD, an automatic
-        // restart can cost hours of progress. The repaired file is only a
-        // fallback for future starts; current containers keep their command-line
-        // RPC args until an operator or update intentionally restarts them.
+        // restart can cost hours of progress. Removing the stale file is
+        // only a fallback for future starts; current containers keep their
+        // command-line RPC args regardless.
         Some(2) => Ok(true),
         _ => {
             warn!("Bitcoin RPC repair helper exited with {}", status);