feat: support multiple SSM parameters for large runner matcher configs (#4790)

[edersonbrilhante]

PR Description

Implements support for splitting the runner matcher configuration across multiple SSM parameters.
PARAMETER_RUNNER_MATCHER_CONFIG_PATH can now accept multiple parameter paths separated by a colon (:).

This avoids SSM size limits for large configurations and improves scalability for environments with many runner types and labels.

Closes #4790

[npalm]

@edersonbrilhante nice contribution. I just tried the parameter split with the multi-runner example in this repo. By adding a few config and adding more labes. Result is I got this error, related to the added foreach

│
│   on ../../modules/webhook/webhook.tf line 27, in resource "aws_ssm_parameter" "runner_matcher_config":
│   27:   for_each = { for idx, val in local.matcher_chunks : idx => val }
│     ├────────────────
│     │ local.matcher_chunks will be known only after apply
│
│ The "for_each" map includes keys derived from resource attributes that cannot be determined until apply, and so Terraform cannot determine the full set of keys that will
│ identify the instances of this resource.
│
│ When working with unknown values in for_each, it's better to define the map keys statically in your configuration and place apply-time results only in the map values.
│
│ Alternatively, you could use the -target planning option to first apply only the resources that the for_each value depends on, and then apply a second time to fully
│ converge.

Wondering you you tested the change? I was not able to get it working right now.