[TT-1396] [CCIP-2804] Migrate CCIP to test secrets

[lukaszcl]

We're updating how we manage test secrets on GitHub CI to enhance security. Instead of passing secrets like the Chainlink image name or wallet key through secrets.toml, we will now load them from the `~/.testsecrets file in your home directory. This change helps us handle secrets more securely.

To set test secrets, see instructions integration-tests/ccip-tests/testconfig/examples/.testsecrets.example

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TODO:

• [x] @kalverra Run tests locally and see if all works fine
• [ ] @kalverra Run all CI workflows and see if it all works fine
• [x] @kalverra Update all documentation (docs in this repo are already updated by lukaszcl)
• [x] @kalverra Notify CCIP developers that this change will be merged soon
• [x] @lukaszcl Merge CTF PR which is a dependecy here https://github.com/smartcontractkit/chainlink-testing-framework/pull/1028/files
• [x] @lukaszcl Update all CI workflows for CCIP
• [x] @lukaszcl Update setup-create-base64-config-ccip in all workflows to correctly use output
• [x] @lukaszcl Allow CI workflows to run with custom test secrets (guide how to run it)

[cl-sonarqube-production[bot]]

Quality Gate passed

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