V0.62.0+ breaks environment variables in config file

[HaroonSaid]

Describe the bug
We have the following in the yaml config file

exporters:
  logging:
    loglevel: debug
  prometheus:
    endpoint: :8889
  jaeger:
    endpoint: ${JAEGER_ENDPOINT}:${JAEGER_PORT}
    tls:
      insecure: true

  prometheusremotewrite:
    endpoint: ${PROMETHEUSREMOTEWRITE}

and pass in the values thru environment variables

Steps to reproduce
Starting with 0.62.0 that no longer works

Error: failed to get config: cannot resolve the configuration: invalid uri: "JAEGER_ENDPOINT}:${JAEGER_PORT"
2022/11/19 19:12:22 collector server run finished with error: failed to get config: cannot resolve the configuration: invalid uri: "JAEGER_ENDPOINT}:${JAEGER_PORT"

What did you expect to see?
Should continue work.

What did you see instead?

What version did you use?
Version: 0.62+

What config did you use?
Config: (e.g. the yaml config file)

Environment
OS: (e.g., "Ubuntu 20.04")
Compiler(if manually compiled): (e.g., "go 14.2")

Additional context
Add any other context about the problem here.

[mx-psi]

Funny, this is something we explicitly discussed as a failure mode here #4742 (comment) cc @bogdandrutu you probably know better where this is failing

[bogdandrutu]

The fix is simple, since the feature is protected by the featuregate: https://github.com/open-telemetry/opentelemetry-collector/blob/main/confmap/resolver.go#L46, just disable that by passing a flag to the command:

./otelcol --feature-gates=-confmap.expandEnabled

Will look into the reason to this fails.

[bogdandrutu]

@HaroonSaid an even better fix for you is to actually change your config and use:

endpoint: "${env:JAEGER_ENDPOINT}"

Since anyway "endpoint" is consider to include the port as well.