Delete TaskMemory tests made redundant by equivalent
ProcessMemoryTests. Some TaskMemory tests are still not redundant
because they test TaskMemory::ReadMapped() or they exercise platform-
specific behavior like TaskMemory::Read() not being able to read a
VM_PROT_NONE page.
Bug: crashpad:263
Change-Id: I72a56b4f3564444b02943f11a0069749bf1b074b
Reviewed-on: https://chromium-review.googlesource.com/c/1387270
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Vlad Tsyrklevich <vtsyrklevich@chromium.org>