Revert "Update test configurations for code serializer"

This reverts commit 9808093e.

Reason for revert: 
https://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20debug/builds/19149

Original change's description:
> Update test configurations for code serializer
> 
> Update test configurations on the bots to test for serializing
> after execute (--cache=after-execute) and producing full code
> cache (--cache=full-code-cache) options. We no longer need
> to test serializing before execute (--cache=code) on the bots.
> 
> Bug: v8:7302
> Change-Id: I123b07028d9231f6da6145b72b62b9ee31352388
> Reviewed-on: https://chromium-review.googlesource.com/869931
> Commit-Queue: Mythri Alle <mythria@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#51235}

TBR=machenbach@chromium.org,yangguo@chromium.org,mythria@chromium.org

Change-Id: I47e03101804194c21b0edf418b744b0ccb66cbf6
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7302
Reviewed-on: https://chromium-review.googlesource.com/913134Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51236}

infra/testing/client.v8.pyl

@@ -17,12 +17,6 @@
     {'name': 'test262_variants', 'variant': 'code_serializer', 'shards': 1},
     {'name': 'benchmarks', 'variant': 'code_serializer', 'shards': 1},
   ],
-  'V8 Linux - debug': [
-    {'name': 'd8testing', 'variant': 'code_serializer_full_code_cache', 'shards': 1},
-    {'name': 'mozilla', 'variant': 'code_serializer_full_code_cache', 'shards': 1},
-    {'name': 'test262_variants', 'variant': 'code_serializer_full_code_cache', 'shards': 1},
-    {'name': 'benchmarks', 'variant': 'code_serializer_full_code_cache', 'shards': 1},
-  ],
   'V8 Linux - gc stress': [
     {'name': 'mjsunit', 'variant': 'slow_path', 'shards': 2},
   ],

tools/testrunner/local/variants.py

@@ -4,8 +4,7 @@
 
 # Use this to run several variants of the tests.
 ALL_VARIANT_FLAGS = {
-  "code_serializer": [["--cache=after-execute"]],
-  "code_serializer_full_code_cache": [["--cache=full-code-cache"]],
+  "code_serializer": [["--cache=code"]],
   "default": [[]],
   "future": [["--future"]],
   # Alias of exhaustive variants, but triggering new test framework features.