a11y: Added aria hidden to expandable button

[rmotwani-c-eightfold]

SUMMARY:

• Added aria-hidden=true to select expandable button as it was not passing aria attribute not allowed check from Accessibility insights tool.
• The button was already out of tab order and with role presentation.

GITHUB ISSUE (Open Source Contributors)

JIRA TASK (Eightfold Employees Only):

Jira task - https://eightfoldai.atlassian.net/browse/ENG-122358

CHANGE TYPE:

• Bugfix Pull Request
• Feature Pull Request

TEST COVERAGE:

• Tests for this change already exist
• I have added unittests for this change

TEST PLAN:

• Go to careers/apply?pid=1970359196742680&domain=microsoft-ta2-dev-sandbox.com
• Login using: rmotwani-c+1@eightfold.ai
• Pass: Microsoft@123
• Run Accessibility insights tool and check if there are no aria-allowed-role error on all the dropdown expand buttons or any element on the page.
• Check screenshots for reference.

Below ss shows the error on the expand and collapse buttons from select input.

The type of elements marked in the below SS are the ones to verify.
Note there are many such elements on the screen.

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

[cpatil-c-eightfold]

LGTM