upkeep: Use char overload of find_last_of where possible
upkeep: Use char overload of find_last_of where possible

Change-Id: Iece01e12059e720e7c9a7cb75e870f145e4c2a17
google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto