Revert "[bazel] Add /depot_tools to $PATH under RBE."
Revert "[bazel] Add /depot_tools to $PATH under RBE."

This reverts commit de68a0a556e4303d07260b1ec1f0634a1cac5ea3.

Reason for revert:

Turns out this wasn't necessary, and it breaks the following tests on RBE:

 - //autoroll/go/repo_manager:repo_manager_test
 - //task_scheduler/go/cacher:cacher_test
 - //task_scheduler/go/job_creation:job_creation_test
 - //task_scheduler/go/syncer:syncer_test
 - //task_scheduler/go/tryjobs:tryjobs_test

Original change's description:
> [bazel] Add /depot_tools to $PATH under RBE.
>
> Follow the below link to see how depot_tools is copied into the RBE toolchain container image:
>
> https://skia.googlesource.com/buildbot/+/eb7cb343e980e844f7e0efc7a6e3543e1e7fd45d/BUILD.bazel#199
>
> Change-Id: I2c2ffe56386007b6c07a565784b2146852a01c91
> Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/410791
> Commit-Queue: Leandro Lovisolo <f558143c2568be8d55575d13f30a1fc5cb8009d5@google.com>
> Reviewed-by: Eric Boren <borenet@google.com>

Change-Id: Id137e5066e27504c49dbb8b55a2b4ed8ab9cf069
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/411016
Reviewed-by: Leandro Lovisolo <f558143c2568be8d55575d13f30a1fc5cb8009d5@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot