BugreportManager takes screenshot even though screenshotFd is null

Bug: 385709501
Fix: 385709501
Flag: android.os.bugreport_deferred_consent_screenshot_fix
Test: atest dumpstate_test
(cherry picked from https://partner-android-review.googlesource.com/q/commit:43f497f573e627e910da037a2a763e7fccec2679)
Merged-In: I6bccb0eb4a005df558ce17ee2d7e323c873c66ad
Change-Id: I6bccb0eb4a005df558ce17ee2d7e323c873c66ad