fix(dora): change lead time calculator

[kostas-petrakis]

Summary

Fixes the issue where the project_pr_metrics link to wrong deployment when prev_success_deployment_commit_id is empty.

Does this close any open issues?

Closes #8188

Screenshots

I builded a local image, and re-run the data collection through my existing project, the results are now correct (compare with data from issue):

{
"project_pr_metrics": [
	{
		"id" : "github:GithubPullRequest:4:1806504909",
		"created_at" : "2024-11-20 17:06:50.350",
		"updated_at" : "2024-11-20 17:06:50.350",
		"_raw_data_params" : "",
		"_raw_data_table" : "",
		"_raw_data_id" : 0,
		"_raw_data_remark" : "",
		"project_name" : "*************",
		"first_commit_sha" : "3726ef9fce54e1f95717ab0fbe695403cbf850ff",
		"pr_coding_time" : 1,
		"first_review_id" : "github:GithubPrReview:4:1979264065",
		"pr_pickup_time" : 4,
		"pr_review_time" : 1429,
		"deployment_commit_id" : "github:GithubRun:4:435823930:8567339272:https:\/\/github.com\/****\/****",
		"pr_deploy_time" : 15,
		"pr_cycle_time" : 1449,
		"first_commit_authored_date" : "2024-04-04 09:07:51",
		"pr_created_date" : "2024-04-04 09:08:03",
		"first_comment_date" : "2024-04-04 09:11:44",
		"pr_merged_date" : "2024-04-05 09:00:16",
		"pr_deployed_date" : "2024-04-05 09:14:22"
	}
]}

[passtas]

One of the issues we are encountering is that it is always assumed that pipeline execution has been performed for Production. Reality is, that likely pipeline has been executed before actual deployment to production, i.e. PR or commit linting, so those pipelines are then counted as actual deployments in DORA dashboards, while such actions are not even considered as a builds.

P.S.: While it wasn't introduced in this specific PR. It may worth starting the discussion around this approach. It may worth creating separate issue.