Revert "[CFI] Enable cfi-icall for official Linux x64 builds"

This reverts commit a6889a09.

Reason for revert: Seeing multiple failures that might be caused by this change: 839362, 838785, 838858, 839327

Original change's description:
> [CFI] Enable cfi-icall for official Linux x64 builds
> 
> The measured size impact is 1.5% and perf impact is ~1%.
> 
> Bug: 701919
> Change-Id: I541242711bc85cc124ff3a2680171577e75475bd
> Reviewed-on: https://chromium-review.googlesource.com/1033918
> Commit-Queue: Peter Collingbourne <pcc@chromium.org>
> Reviewed-by: Peter Collingbourne <pcc@chromium.org>
> Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#554828}

TBR=dpranke@chromium.org,pcc@chromium.org,vtsyrklevich@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 701919
Change-Id: Ia73c2508483576a16fbc00749f081f013e6fd813
Reviewed-on: https://chromium-review.googlesource.com/1042765Reviewed-by: Peter Collingbourne <pcc@chromium.org>
Commit-Queue: Peter Collingbourne <pcc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555853}

build/config/sanitizers/sanitizers.gni

@@ -61,8 +61,7 @@ declare_args() {
   # Enable checks for indirect function calls via a function pointer.
   # TODO(pcc): remove this when we're ready to add these checks by default.
   # https://crbug.com/701919
-  use_cfi_icall = target_os == "linux" && !is_chromeos && target_cpu == "x64" &&
-                  is_official_build
+  use_cfi_icall = false
 
   # Print detailed diagnostics when Control Flow Integrity detects a violation.
   use_cfi_diag = false