Rename checkPrivilegedPermissionAllowlist()

Rename method checkPrivilegedPermissionAllowlist() to avoid
confusions on understanding the code.

We could also split this method into shouldCheckAllowlist()
and checkAllowlist() to avoid the confusion. However, since
we will always call these two methods together, it's cleaner
to put these two together. Hence renamed this method to
checkPrivilegedPermissionAllowlistIfNeeded(). Also added doc
to explain the return values.

Bug: 364435115
Test: Build
Flag: DOCS_ONLY
Change-Id: I8071b6860da4853c7a74e1d2daf1748ccb6cbd6e