Delete marketstack EA

[dskloetc]

Description

We have many EAs which are not referenced from either RDD or infra-k8s and are also not referenced by other EAs.

Some of these might still be used in other ways, as discussed here.

But @thomjg confirmed that marketstack is one of the EAs that is not used anywhere.

Changes

As separate commits:

1. git rm -r packages/sources/marketstack/
2. git grep -l marketstack and made manual changes in some of those files.
3. yarn
4. changeset

Steps to Test

N/A

Quality Assurance

• 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.
• The branch naming follows git flow (feature/x, chore/x, release/x, hotfix/x, fix/x) or is created from Jira.
• This is related to a maximum of one Jira story or GitHub issue.
• Types are safe (avoid TypeScript/TSLint features like any and disable, instead use more specific types).
• 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.

[changeset-bot]

🦋 Changeset detected

Latest commit: dc5658a

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@chainlink/ea-scripts	Patch

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