Revert "yaml: use safe_load"

This reverts commit 86f3706433cf52c04ad1eca2a02d910942ffd4d5.

Reason for revert: This might cause b/188594398, which many snapshot builds failed. 

Original change's description:
> yaml: use safe_load
>
> This silences warnings, might be safer too!
>
> BUG=None
> TEST=cq + units
>
> Change-Id: I2398d05d56f783db931ebaacf48f9c86205fe865
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2903129
> Commit-Queue: George Engelbrecht <engeg@google.com>
> Tested-by: George Engelbrecht <engeg@google.com>
> Reviewed-by: Jack Neus <jackneus@google.com>
> Reviewed-by: LaMont Jones <lamontjones@chromium.org>
> Reviewed-by: Mike Frysinger <vapier@chromium.org>

Bug: None
Change-Id: Ibdeb5342a6d4d29552cb22ecdfcb0284e3929e81
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2903471
Reviewed-by: Chih-Yu Huang <akahuang@chromium.org>
Commit-Queue: Chih-Yu Huang <akahuang@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Tested-by: Chih-Yu Huang <akahuang@chromium.org>
Owners-Override: Chih-Yu Huang <akahuang@chromium.org>
Auto-Submit: Chih-Yu Huang <akahuang@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
diff --git a/scripts/tricium_clang_tidy.py b/scripts/tricium_clang_tidy.py
index 4e3fa4e..93fd68b 100644
--- a/scripts/tricium_clang_tidy.py
+++ b/scripts/tricium_clang_tidy.py
@@ -361,7 +361,7 @@
                          f'{json_file}. Output:\n{meta.stdstreams}')
 
     with yaml_file.open('rb') as f:
-      yaml_data = yaml.safe_load(f)
+      yaml_data = yaml.load(f)
     return meta, list(parse_tidy_fixes_file(Path(meta.wd), yaml_data))
   except Exception:
     return ExceptionData()
@@ -486,8 +486,8 @@
 
   results = set()
   # If clang-tidy dumps a lot of diags, it can take 1-10secs of CPU while
-  # holding the GIL to |yaml.safe_load| on my otherwise-idle dev box.
-  # |yaml_pool| lets us do this in parallel.
+  # holding the GIL to |yaml.load| on my otherwise-idle dev box. |yaml_pool|
+  # lets us do this in parallel.
   with multiprocessing.pool.Pool() as yaml_pool:
     for ebuild in ebuild_list:
       lint_tmpdir = generate_lints(board, ebuild.ebuild_path)