Add api for cts test to ignore plmn list from storage Bug: 415139661 Test: make Flag: EXEMPT bugfix (cherry picked from https://googleplex-android-review.googlesource.com/q/commit:5ad9e39e17de307d62e5044189e50cb635954957) Merged-In: I1b72121e6170741d363af2d6b26db7840ae9298d Change-Id: I1b72121e6170741d363af2d6b26db7840ae9298d