This is a reland of d61a9347

6th attempt. Relanding after fixing TSan/UBSan issues.

Original change's description:
> [ptr-compr][x64] Temporarily enable pointer compression on x64
>
> ... and make sure that the x64 ptr-compr bots proceed testing V8 without
> pointer compression in order to keep testing the full pointer mode.
>
> Bug: v8:7703
> Change-Id: Ib1498609603cb03be2464043658131d5a2f1e012
> Cq-Include-Trybots: luci.v8.try:v8_linux64_ubsan_rel_ng,v8_linux64_tsan_rel
> Cq-Include-Trybots: luci.chromium.try:fuchsia_x64,linux-rel,mac-rel
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1559850
> Commit-Queue: Igor Sheludko <ishell@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61416}

Bug: v8:7703
Change-Id: I1fa0989aef9ea08e54fd6dfd32d6989367332ce3
Cq-Include-Trybots: luci.v8.try:v8_linux64_ubsan_rel_ng,v8_linux64_tsan_rel
Cq-Include-Trybots: luci.v8.try:v8_linux64_cfi_rel_ng
Cq-Include-Trybots: luci.chromium.try:fuchsia_x64,linux-rel,mac-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1607654
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61559}