Revert "[heap] Remove MinorMC variant from bots"

This reverts commit 7c64e5b4.

Reason for revert: MinorMC passes all CQ bots again (crrev.com/c/3872266)

Original change's description:
> [heap] Remove MinorMC variant from bots
>
> As part of revising MinorMC, it would soon be broken and bots should
> not be red because of it.
>
> Bug: v8:12612
> Change-Id: I0551d0a115ac2f4fa7fc32190458850f80b84cf5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3810353
> Commit-Queue: Omer Katz <omerkatz@chromium.org>
> Reviewed-by: Almothana Athamneh <almuthanna@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82197}

Bug: v8:12612
Change-Id: I4a08f79efc3b5fc133a0a920a11d2af559b5bf4f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3885890
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Almothana Athamneh <almuthanna@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83191}

infra/testing/builders.pyl

@@ -376,6 +376,7 @@
       {'name': 'test262', 'variant': 'extra', 'shards': 9},
       {'name': 'v8testing', 'shards': 5},
       {'name': 'v8testing', 'variant': 'extra', 'shards': 5},
+      {'name': 'v8testing', 'variant': 'minor_mc'},
       {'name': 'v8testing', 'variant': 'no_lfa'},
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
       {'name': 'v8testing', 'variant': 'stress_concurrent_allocation'},
@@ -592,6 +593,7 @@
       {'name': 'v8initializers'},
       {'name': 'v8testing', 'shards': 2},
       {'name': 'v8testing', 'variant': 'extra', 'shards': 2},
+      {'name': 'v8testing', 'variant': 'minor_mc'},
       {'name': 'v8testing', 'variant': 'no_lfa'},
       {'name': 'v8testing', 'variant': 'slow_path'},
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
@@ -1257,6 +1259,7 @@
       {'name': 'v8testing'},
       {'name': 'v8testing', 'variant': 'assert_types'},
       {'name': 'v8testing', 'variant': 'extra'},
+      {'name': 'v8testing', 'variant': 'minor_mc'},
       {'name': 'v8testing', 'variant': 'no_lfa'},
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},
       # Maglev -- move to extra once more architectures are supported.
@@ -1316,6 +1319,7 @@
       {'name': 'test262', 'variant': 'extra', 'shards': 5},
       {'name': 'v8testing', 'shards': 2},
       {'name': 'v8testing', 'variant': 'extra', 'shards': 2},
+      {'name': 'v8testing', 'variant': 'minor_mc'},
       {'name': 'v8testing', 'variant': 'no_lfa'},
       {'name': 'v8testing', 'variant': 'slow_path'},
       {'name': 'v8testing', 'variant': 'stress_instruction_scheduling'},