Add preinstall allowlist for ImsMedia

- From Android 17, it is mandatory to include preinstall allowlisting
  for all preinstalled packages.
- This change adds a system config XML to allowlist
  com.android.telephony.imsmedia for SYSTEM user type.

BYPASS_INSTALL_IN_SYSTEM_REASON=system service restricted to system user
Bug: 456165911
Test: atest ImsMediaJavaUnitTests
Flag: EXEMPT BUGFIX
Change-Id: I01c7331ee309a5bbf24d95dee73d61b67361ba46

Change-Id: I8487979fe5114db31b8695c78df7ebc3115387ed