Refactoring E2E test classes

[TeixeiraES]

Fix

Describe changes proposed in this pull request:

• In AbstractE2ETest class, a Protected Constructor was added to prevent the abstract from being instantiated incorrectly
• In AbstractE2ETest class, the method registerProperties changed to public static void
• A new class, E2ETestUtils, was created extracting the test tool methods from AlterationEnrichmentControllerE2ETest and ColumnStoreMutationControllerE2ETest in order to eliminate duplicate code, separate test and tooling concerns and refactor two god class smells

Checks

• [✓] The commit log is comprehensible. It follows 7 rules of great commit messages. We can fix this during merge by using a squash+merge if necessary
• [✓] Has tests or has a separate issue that describes the types of test that should be created. If no test is included it should explicitly be mentioned in the PR why there is no test.
• [✓] Is this PR adding logic based on one or more clinical attributes? If yes, please make sure validation for this attribute is also present in the data validation / data loading layers (in backend repo) and documented in File-Formats Clinical data section!
• [✓] Make sure your PR has one of the labels defined in https://github.com/cBioPortal/cbioportal/blob/master/.github/release-drafter.yml

Any screenshots or GIFs?

No, this is not GUI related

• title: '🧹 Cleanup & Refactoring 🔧'
  labels:
  • 'refactoring'
• title: '👷‍♀️ Testing, Configuration & Deployment'
  labels:
  • 'test'