Revert "fix: fix show bgp summary output typo" (sonic-net#3423)

Reverts sonic-net#3375

It will impact many automation scripts that the community users may have developped for years... So if we change it now, all those scripts will be impacted... not something we want to do just to correct a miss spelled word at this stage...
Revert this change

What I did
Reverts fix: fix show bgp summary output typo sonic-net#3375
Add comments in case someone else fix the typo without notification.

co-authorized by: [email protected]

Author: yejianquan