Add flag FLAG_ACTIVITY_CLEAR_TOP to reopen existing Activity

In case ESOS questionnaire is invoked several times without exit, only a single instance of questionnaire is shown at one time.

Bug: 349145955
Flag: EXEMPT bugfix
Test: manual e2e test using shieldbox for both T911 and ESOS
Test: 352761121
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:87ca3eb44c85dd371398feb9bdc0790729ab3f91)
Merged-In: I4662939fa98b66fec77ff257ff33128580e1959e
Change-Id: I4662939fa98b66fec77ff257ff33128580e1959e