oracledb_cdc: handle LOB_TRIM redo SQL separately from SELECT_LOB_LOCATOR

[josephwoodward]

Addresses an issue where LOB_TRIM events were being incorrectly handled by splitting OpLobTrim into its own case, since LOB_TRIM always follows a SELECT_LOB_LOCATOR in the same transaction.

[claude]

Commits
LGTM

Review
This is a focused bug fix that splits OpLobTrim handling out of the OpSelectLobLocator case in internal/impl/oracledb/logminer/logminer.go. The previous code path attempted to parse the LOB_TRIM SQL with ParseSelectLobLocator, which would have failed because LOB_TRIM's redo SQL is dbms_lob.trim(loc_b, N) rather than a SELECT ... INTO ... FROM statement. The new case correctly relies on the active LOB key established by a preceding SELECT_LOB_LOCATOR and clears the accumulator fragments to prepare for subsequent LOB_WRITE events. Nil/existence guards are in place.

LGTM