Allow for multiple sets of keys to be used in the Harris-and-trotter EA

Closes #DF-20228

Select different API_KEY env variable based on input param

[ ] If a new adapter was made, or an existing one was modified so that its environment variables have changed, update the relevant infra-k8s configuration file.
[ ] If a new adapter was made, or an existing one was modified so that its environment variables have changed, update the relevant adapter-secrets configuration file or update the soak testing blacklist.
[ ] If a new adapter was made, or a new endpoint was added, update the test-payload.json file with relevant requests.
[x] The branch naming follows git flow (feature/x, chore/x, release/x, hotfix/x, fix/x) or is created from Jira.
[x] This is related to a maximum of one Jira story or GitHub issue.
[x] Types are safe (avoid TypeScript/TSLint features like any and disable, instead use more specific types).
[x] All code changes have 100% unit and integration test coverage. If testing is not applicable or too difficult to justify doing, the reasoning should be documented explicitly in the PR.