[automerger skipped] Update Security String to 2021-09-01 am: 639164b255 am: 996d1d3a4f am: abecfaa90f am: 28bb26cec7 -s ours am: 76530937da -s ours

am skip reason: Merged-In Icea699ec7f82744ff0a6dca90068b2737129778a with SHA-1 cfd4896dc2 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/15123745

Change-Id: I860c4eceb7fa11c996b16ca660f81027398ff617