chore: Add null check to the Bitbucket Server URL parser

[vinokurig]

What does this PR do?

Fix the NullPointerException when starting a workspace from a BItbucket Server repository URL copied from browser's address bar.

Screenshot/screencast of this PR

What issues does this PR fix or reference?

fixes eclipse-che/che#23766

How to test this PR?

1. Deploy Che from the pull request image: quay.io/eclipse/che-server:pr-983
2. Configure Bitbucket Server oauth
3. Start a workspace from the Bitbucket Server repository URL copied from browser's address bar, e.g. https://<bitbucket server host>/users/<user>/repos/<repository name>/browse. Important: the default branch must be used, if a non default branch is selected the url will contain an additional query parameter (?at=<branch reference>).
4. See: workspace starts without any errors.

PR Checklist

As the author of this Pull Request I made sure that:

• The Eclipse Contributor Agreement is valid
• Code produced is complete
• Code builds without errors
• Tests are covering the bugfix
• The repository devfile is up to date and works
• Sections What issues does this PR fix or reference and How to test this PR completed
• Relevant user documentation updated
• Relevant contributing documentation updated
• CI/CD changes implemented, documented and communicated

Release Notes

Reviewers

Reviewers, please comment how you tested the PR when approving it.

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: tolusha, vinokurig

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[github-actions]

Docker image build succeeded: quay.io/eclipse/che-server:pr-983

kubectl patch command

kubectl patch -n eclipse-che "checluster/eclipse-che" --type=json -p="[{"op": "replace", "path": "/spec/components/cheServer/deployment", "value": {containers: [{image: "quay.io/eclipse/che-server:pr-983", name: che}]}}]"

[vinokurig]

/retest