Prepare for BMO main branch switch

[kashifest]

This PR prepares the prow config for BMO main branch switch. Mainly this PR adds the branch monitoring for BMO in prow config. Currently it monitors two branches main and master. Once main is the default branch, master would be removed.

[kashifest]

/assign @fmuyassarov
/cc @furkatgofurov7 @macaptain @smoshiur1237

[kashifest]

/test-v1b1-integration

[smoshiur1237]

/lgtm

[fmuyassarov]

/approve

[metal3-io-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fmuyassarov, smoshiur1237

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[metal3-io-bot]

@kashifest: Updated the config configmap in namespace prow at cluster default using the following files:

• key config.yaml using file prow/config/config.yaml

In response to this:

This PR prepares the prow config for BMO main branch switch. Mainly this PR adds the branch monitoring for BMO in prow config. Currently it monitors two branches main and master. Once main is the default branch, master would be removed.

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