[Backport 2.x] fix build errors caused by filterIndices method being moved from SnapshotUtils to IndexUtils (#4312)

[cwperks]

Backport #4313 to 2.x

Also includes the version increment from #4311

[cwperks]

I pulled the version increment to 2.15.0 into this PR too: #4311

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.17%. Comparing base (5961118) to head (ed6c073).

Additional details and impacted files

@@           Coverage Diff           @@
##              2.x    #4319   +/-   ##
=======================================
  Coverage   66.16%   66.17%           
=======================================
  Files         301      301           
  Lines       21580    21580           
  Branches     3513     3513           
=======================================
+ Hits        14279    14280    +1     
  Misses       5543     5543           
+ Partials     1758     1757    -1     

Files	Coverage Δ
...earch/security/resolver/IndexResolverReplacer.java	68.01% <100.00%> (ø)
...search/security/support/SnapshotRestoreHelper.java	82.75% <100.00%> (ø)

... and 1 file with indirect coverage changes