Allow overriding USE_SECONDARY_MAP

[opsengine]

Make USE_SECONDARY_MAP configurable to mitigate #11968

Need to add a way to propagate the macro as a build flag from bundle.

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[haberman]

Please add the test case #11968 as a unit test, and enable USE_SECONDARY_MAP by default.

We can make it conditional again when/if we have a fix that can pass the test.

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