[SP24] Rename functions that add Entry unconditionally

Currently, in NetworkStats, there are many methods to manipulate
the records. However, some methods are similar and ambiguous,
such as addEntry, addValues, setValues, addIfaceValues,
combineValues and combineAllValues.

Thus, properly grouping and renaming methods are necessary.
In this change, for methods that add one record unconditionally,
name them insertEntry.
  setIfaceValues -> insertEntry
  addEntry -> insertEntry

Test: atest FrameworksNetTests ImsPhoneCallTrackerTest TetheringTests
Test: m doc-comment-check-docs
Bug: 148895143
Change-Id: I801ddc49e283a254b9586700c9b597c0adb0d459