Bazel: Remove --spawn_strategy and --strategy options for RBE
Bazel: Remove --spawn_strategy and --strategy options for RBE

In Bazel@HEAD this warning is issued when building on RBE:

WARNING: Use of implicit local fallback will go away soon, please
set a fallback strategy instead. See --legacy_local_fallback option.

Since release 0.27 Bazel auto detects the execution strategy, if no
strategy flag is provided. If none of the strategy flags was used,
Bazel will generate a default list of strategies (in this order):

   remote,worker,sandboxed,local

and, for every action it wants to execute, will pick up the first
strategy that can execute it.

See this blog entry for more details: [1].

[1] https://blog.bazel.build/2019/06/19/list-strategy.html

Change-Id: I6a700515fd861b947d57f003d6d1a19693dc37ed

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