Fix revive identified linter issues: exported

[janardhanvissa]

#7444

Fixed below linter issues:

• 83 exported

Release Note: None

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.92%. Comparing base (e4b09f1) to head (ffea7f6).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7553      +/-   ##
==========================================
+ Coverage   81.82%   81.92%   +0.09%     
==========================================
  Files         362      362              
  Lines       27834    27832       -2     
==========================================
+ Hits        22776    22802      +26     
+ Misses       3850     3834      -16     
+ Partials     1208     1196      -12     

Files with missing lines	Coverage Δ
balancer/endpointsharding/endpointsharding.go	66.92% <ø> (ø)
balancer/pickfirst/pickfirst.go	83.73% <ø> (ø)
credentials/tls/certprovider/pemfile/builder.go	100.00% <ø> (ø)
internal/balancer/gracefulswitch/config.go	82.60% <ø> (ø)
internal/channelz/channel.go	79.80% <ø> (ø)
internal/channelz/server.go	90.69% <ø> (ø)
internal/channelz/socket.go	46.66% <ø> (ø)
internal/channelz/subchannel.go	96.00% <ø> (ø)
internal/channelz/trace.go	92.15% <ø> (ø)
internal/idle/idle.go	89.15% <ø> (ø)
... and 2 more

... and 24 files with indirect coverage changes

[purnesh42H]

@janardhanvissa please open this in your fork first for review