Revert 7e81c4b2901d8a692c before merge this branch to master

[pengzhout]

As discussed, we need to revert 7e81c4b first before merging this branch to GPDB master.

GPDB master is now derived from PG_94_STABLE in which 7e81c4b reverted some commits. however, PG_95 still keep those commits reverted by 7e81c4b.

A note from daniel:

let's make a note of it to ensure that we cherry-pick it into master just before the merge, so that the reverted commit isn’t introduced as part of the merge where it shouldn’t be

[pengzhout]

After a second thought, 9.5 merge PR have reverted 7e81c4b, it is acceptable to make it as part of merge, the commit message of 7e81c4b explained the two commits it reverted should be kept in 9.5.