[benchmarking] updated estimate for base_perftests

The current estimate of base_perftests is inaccurate. Updating the value based on actual runtime.

Bug: chromium:1130157
Change-Id: I7f6ca8e4f8772259cda617803385ac83fbb7daa5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2473039
Commit-Queue: Wenbin Zhang <wenbinzhang@google.com>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817681}

tools/perf/core/bot_platforms.py

@@ -320,7 +320,7 @@ _LINUX_BENCHMARK_CONFIGS = PerfSuite(OFFICIAL_BENCHMARK_CONFIGS).Remove([
 ])
 _LINUX_EXECUTABLE_CONFIGS = frozenset([
     # TODO(crbug.com/811766): Add views_perftests.
-    _base_perftests(),
+    _base_perftests(10),
     _load_library_perf_tests(),
     _media_perftests(),
     _net_perftests(),
@@ -332,7 +332,7 @@ _MAC_HIGH_END_BENCHMARK_CONFIGS = PerfSuite(OFFICIAL_BENCHMARK_CONFIGS).Remove([
     'v8.runtime_stats.top_25',
 ])
 _MAC_HIGH_END_EXECUTABLE_CONFIGS = frozenset([
-    _base_perftests(),
+    _base_perftests(10),
     _dawn_perf_tests(330),
     _media_perftests(),
     _net_perftests(),
@@ -357,7 +357,7 @@ _WIN_10_BENCHMARK_CONFIGS = PerfSuite(OFFICIAL_BENCHMARK_CONFIGS).Remove([
 ])
 _WIN_10_EXECUTABLE_CONFIGS = frozenset([
     _angle_perftests(),
-    _base_perftests(),
+    _base_perftests(20),
     _components_perftests(),
     _dawn_perf_tests(600),
     _media_perftests(),