[build][test] Remove configs for removed builders

NOTRY=true

Bug: chromium:933093
Change-Id: Ic3c164d72a74def2b3ad559a67163d7f497caa9c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1528434Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60355}

infra/mb/mb_config.pyl

@@ -91,9 +91,6 @@
       # Misc.
       'V8 Linux gcc': 'release_x86_gcc_no_goma',
       'V8 Linux64 gcc - debug': 'debug_x64_gcc_no_goma',
-      # TODO(machenbach): Remove after switching.
-      'V8 Linux gcc 4.8': 'release_x86_gcc',
-      'V8 Linux64 gcc 4.8 - debug': 'debug_x64_gcc',
       # FYI.
       'V8 Linux64 - pointer compression': 'release_x64_pointer_compression',
       'V8 Linux64 - arm64 - sim - pointer compression - builder':
@@ -483,8 +480,6 @@
       'debug_bot', 'x64', 'v8_snapshot_custom'],
     'debug_x64_fuchsia': [
       'debug_bot', 'x64', 'fuchsia'],
-    'debug_x64_gcc': [
-      'debug_bot', 'x64', 'gcc'],
     'debug_x64_gcc_no_goma': [
       'debug', 'shared', 'v8_enable_slow_dchecks', 'v8_optimized_debug', 'x64',
       'gcc', 'no_goma'],
@@ -529,8 +524,6 @@
       'release_bot', 'x86', 'v8_no_enable_embedded_builtins'],
     'release_x86_noembed_trybot': [
       'release_trybot', 'x86', 'v8_no_enable_embedded_builtins'],
-    'release_x86_gcc': [
-      'release_bot', 'x86', 'gcc'],
     # TODO(machenbach): Enable back goma once supported.
     'release_x86_gcc_minimal_symbols': [
       'release', 'static', 'x86', 'gcc', 'minimal_symbols', 'no_goma'],

infra/testing/builders.pyl

@@ -739,15 +739,6 @@
       {'name': 'v8testing'},
     ],
   },
-  # TODO(machenbach): Remove after switching.
-  'V8 Linux gcc 4.8': {
-    'swarming_dimensions' : {
-      'os': 'Ubuntu-16.04',
-    },
-    'tests': [
-      {'name': 'v8testing'},
-    ],
-  },
   'V8 Linux64': {
     'swarming_dimensions': {
       'cpu': 'x86-64-avx2',