Issue enforcing quoted values in config

[MovieStoreGuy]

Describe the bug

When providing a configuration that uses the env provider, it does not preserve the quotes around the "${env:...}".

This means when a complaint time RFC string is supplied, it gets converted into a time.Time value instead of the expected string, which then stops the config from being valid.

Steps to reproduce

1. Set an env var with a timestamp value
   a. export BUILT_TS="2006-01-02T15:04:05Z07:00"
2. Reference var in configuration.
   a. value : "${env:BUILT_TS}"
3. Have collector run with configuration using reference variable.

What did you expect to see?
Considering the provider is in quotes, it should not strip those values

What did you see instead?
Upon running the collector with the provider configuration, the error is show as:

Error: failed to get config: cannot resolve the configuration: unsupported type=time.Time for retrieved config, ensure that values are wrapped in quotes

What version did you use?
v0.105.0

What config did you use?

processors:
  resource/static:
    attributes:
    - key: build.version
      action: insert
      value: "${BUILD_VERSION}"

Environment
Linux, go v1.23.4

Additional context
I've tried a few different combinations, but this currently works in v0.103.0 but upgrading to v0.105.0 surfaced this.

I've also tried:

\"${env:var}\" # Didn't work with error: retrieved value does not have unambiguous string representation: <nil>
"${env:var}"  # moved to calling the env provider directly, same error as reported

[mx-psi]

I believe #10618 would fix this, I will add a test on this specific case.

[TylerHelmuth]

@MovieStoreGuy I was not able to reproduce this on v0.105.0 in a binary or the confmap e2e test from my local computer (macos, arm46).

export BUILT_TS="2006-01-02T15:04:05Z07:00"

receivers:
  nop:

processors:
  resource:
    attributes:
      - key: build.version
        value: "${env:BUILT_TS}"
        action: insert

exporters:
  nop:

service:
  telemetry:
    logs:
      level: debug
  pipelines:
    traces:
      receivers:
        - nop
      processors:
        - resource
      exporters:
        - nop

And in the confmap e2e tests the following tests pass:

{
	value:       "2006-01-02T15:04:05Z07:00",
	targetField: TargetFieldString,
	expected:    "2006-01-02T15:04:05Z07:00",
},
{
	value:       "2006-01-02T15:04:05Z07:00",
	targetField: TargetFieldInlineString,
	expected:    "inline field with 2006-01-02T15:04:05Z07:00 expansion",
},

[TylerHelmuth]

I believe this is the root cause of the issue

if uri == input {
		// If the value is a single URI, then the return value can be anything.
		// This is the case `foo: ${file:some_extra_config.yml}`.
		ret, err := mr.expandURI(ctx, input)
		if err != nil {
			return input, false, err
		}

		expanded, err := ret.AsRaw()
		if err != nil {
			return input, false, err
		}
		return expanded, true, err
	}

When the env var being expanded is the entire string, it is expanded and the returned value and it's type is kept as is. I agree that @mx-psi PR will fix the issue.

In the meantime you can use str!! ${env:BUILT_TS} or add "" to the env var value.