pgsql: Remove spurious code comments in standby related code

Remove spurious code comments in standby related code

GetRunningTransactionData() suggested that subxids were not worth
optimizing away if overflowed, yet they have already been removed
for that case.

Changes to LogAccessExclusiveLock() API forgot to remove the
prior comment when it was copied to LockAcquire().

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/dc878ffedf2aa461b11b617094101e3c4cf48daa

Modified Files
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src/backend/storage/ipc/procarray.c | 4 +---
src/backend/storage/ipc/standby.c   | 5 -----
2 files changed, 1 insertion(+), 8 deletions(-)