Remove old `V2_AWS_SESSION_TOKEN` references from deploy workflows

[jtherrmann]

Jira: https://asfdaac.atlassian.net/browse/TOOL-4693

Note: The above link is accessible only to members of ASF.

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The V2_AWS_SESSION_TOKEN secret is referenced in several of our deployment workflows:

$ git grep V2_AWS_SESSION_TOKEN
.github/workflows/deploy-custom-prod.yml:          aws-session-token: ${{ secrets.V2_AWS_SESSION_TOKEN }}
.github/workflows/deploy-custom-test.yml:          aws-session-token: ${{ secrets.V2_AWS_SESSION_TOKEN }}
.github/workflows/deploy-daac-prod.yml:          aws-session-token: ${{ secrets.V2_AWS_SESSION_TOKEN }}
.github/workflows/deploy-daac-test.yml:          aws-session-token: ${{ secrets.V2_AWS_SESSION_TOKEN }}
.github/workflows/deploy-edc-sandbox.yml:          aws-session-token: ${{ secrets.V2_AWS_SESSION_TOKEN }}
.github/workflows/deploy-plus-prod.yml:          aws-session-token: ${{ secrets.V2_AWS_SESSION_TOKEN }}
.github/workflows/deploy-plus-test.yml:          aws-session-token: ${{ secrets.V2_AWS_SESSION_TOKEN }}

But I don't think we use it anymore, and it's not defined in https://github.com/ASFHyP3/hyp3/settings/secrets/actions so we can probably just delete those lines in our deploy workflows.

This will also be automatically done if we switch to OIDC: https://github.com/ASFHyP3/hyp3-oidc/issues/2