Revert "core/rawdb: open meta file in read only mode (#26009)"

[NathanBSC]

Description

This reverts commit b9ba6f6e4d86d0ee86c63e8f4552e233fe0450aa.

Rationale

dir chaindata generated by old version of geth(before big merge) doesn't contain *meta files which are used to tail deletion.
so for back-compatible, still open meta file in append mode even readonly flagged.

Example

add an example CLI or API response...

Changes

Notable changes:

• add each change in a bullet point here
• ...

[fynnss]

LGTM.

Without this pr, It'll return "*.meta file: no such file or directory" error when open historical bsc snapshot database as readonly.

# ./geth db stats --datadir server/data-seed/
INFO [09-19|04:13:45.869] Maximum peer count                       ETH=50 LES=0 total=50
INFO [09-19|04:13:45.871] Smartcard socket not found, disabling    err="stat /run/pcscd/pcscd.comm: no such file or directory"
INFO [09-19|04:13:45.875] Set global gas cap                       cap=50,000,000
INFO [09-19|04:13:45.875] Initializing the KZG library             backend=gokzg
INFO [09-19|04:13:46.293] Using leveldb as the backing database
INFO [09-19|04:13:46.293] Allocated cache and file handles         database=/server/server/data-seed/geth/chaindata cache=408.00MiB handles=4096 readonly=true
INFO [09-19|04:13:54.841] Using LevelDB as the backing database
INFO [09-19|04:13:54.847] Found legacy ancient chain path          location=/server/server/data-seed/geth/chaindata/ancient
Chain metadata
  databaseVersion: 8 (0x8)
  headBlockHash: 0x6eab3c4761643ae9817382596332a98bbbbd6cd7ed3c870327decef37fd7711b
  headFastBlockHash: 0x6eab3c4761643ae9817382596332a98bbbbd6cd7ed3c870327decef37fd7711b
  headHeaderHash: 0x6eab3c4761643ae9817382596332a98bbbbd6cd7ed3c870327decef37fd7711b
  lastPivotNumber: 6920578 (0x699982)
  len(snapshotSyncStatus): 0 bytes
  snapshotDisabled: false
  snapshotJournal: 2991918 bytes
  snapshotRecoveryNumber: 31435739 (0x1dfabdb)
  snapshotRoot: 0xf2034e8566930e7ed51956d27bdfeec0d151c76c09fb2681f0f644e79acf6a12
  txIndexTail: 0 (0x0)
  fastTxLookupLimit: 2350000 (0x23dbb0)


Fatal: Could not open database: open /server/server/data-seed/geth/chaindata/ancient/headers.meta: no such file or directory