Fix string conversion for CI Inputs

What does this MR do and why?

Fix string conversion for CI Inputs

We should not try to parse the string inputs as JSON because anyone can pass anything into it.

References

Related to #535995 (closed)

Screenshots or screen recordings

spec:
  inputs:
    hash_as_string:
      default: 'normal string'
---

test:
  script:
    - echo $[[ inputs.hash_as_string ]]

Before	After

Before	After

Before	After

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.