servicemanager: set consistent flags for self-reg

SM has special flags set to become a context object, but
these were not set when it registers as itself.

Bug: 382775095
Test: boot w/ harsher checks
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:6ac542d1d0420f97ddef52991533662e96760fa9)
Merged-In: I0fb567cbcca67a2fc6c088f652c8af570b8d7e53
Change-Id: I0fb567cbcca67a2fc6c088f652c8af570b8d7e53