Revert "Add -fsanitize=pointer-overflow to the UBSan config"

This reverts commit 103f0ee63afb8a42af04c9a152dc938e3571c128.

Reason for revert:
LUCI Bisection has identified this change as the cause of a test failure. See the analysis: https://ci.chromium.org/ui/p/chromium/bisection/test-analysis/b/6268777520955392

Sample build with failed test: https://ci.chromium.org/b/8727726349902573329
Affected test(s):
[ninja://third_party/leveldatabase:leveldb_unittests/HASH.SignedUnsignedIssue](https://ci.chromium.org/ui/test/chromium/ninja:%2F%2Fthird_party%2Fleveldatabase:leveldb_unittests%2FHASH.SignedUnsignedIssue?q=VHash%3A3f633ebc23c0d63e)

If this is a false positive, please report it at http://b.corp.google.com/createIssue?component=1199205&description=Analysis%3A+https%3A%2F%2Fci.chromium.org%2Fui%2Fp%2Fchromium%2Fbisection%2Ftest-analysis%2Fb%2F6268777520955392&format=PLAIN&priority=P3&title=Wrongly+blamed+https%3A%2F%2Fchromium-review.googlesource.com%2Fc%2Fchromium%2Fsrc%2F%2B%2F6108769&type=BUG

Original change's description:
> Add -fsanitize=pointer-overflow to the UBSan config
>
> This required adding a couple suppressions for issues. Also fixing
> undefined behavior in BufferIteratorTest.ObjectSizeOverflow, which seems
> to have not been testing SIZE_MAX at all, and just when the buffer
> didn't have enough room.
>
> Bug: 40942951, 384391188, 385062729, 385155394
> Change-Id: If6defef3fbc4977632fccc63049901836d4a5347
> Cq-Include-Trybots: luci.chromium.try:linux_chromium_ubsan_rel_ng
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6108769
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Auto-Submit: David Benjamin <davidben@chromium.org>
> Commit-Queue: David Benjamin <davidben@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1399851}
>

Bug: 40942951, 384391188, 385062729, 385155394
Change-Id: Ife732bdde2500d537051c17f3793880a5755414e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6120213
Owners-Override: Phillis Tang <phillis@chromium.org>
Reviewed-by: Phillis Tang <phillis@chromium.org>
Commit-Queue: Phillis Tang <phillis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1399914}
NOKEYCHECK=True
GitOrigin-RevId: 9804941d6b648c7c4d4d7a2460e4a4a661b160b0

Author: luci-bisection@appspot.gserviceaccount.com

config/sanitizers/BUILD.gn

@@ -543,7 +543,6 @@ config("ubsan_flags") {
       "-fsanitize=null",
       "-fsanitize=nonnull-attribute",
       "-fsanitize=object-size",
-      "-fsanitize=pointer-overflow",
       "-fsanitize=return",
       "-fsanitize=returns-nonnull-attribute",
       "-fsanitize=shift",