fix: creation of contact, customer, opportunity, quotation and prospect from lead (backport #42014)

[mergify]

versions: dev & 15

fixes: #42009

Before:

• In v15, if there is an existing contact, then "Create Contact" shouldn't appear.
• In dev, customer, opportunity, and prospect creation fail (because of this PR: fix: correct creation of opportunity with lead dashboard plus button #40987).

Before_Lead.mov

After:

after_lead.mp4

---

This is an automatic backport of pull request #42014 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 8304d19 has failed:

On branch mergify/bp/version-15-hotfix/pr-42014
Your branch is up to date with 'origin/version-15-hotfix'.

You are currently cherry-picking commit 8304d19e8b.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   erpnext/crm/doctype/lead/lead.js

no changes added to commit (use "git add" and/or "git commit -a")

Cherry-pick of 5844897 has failed:

On branch mergify/bp/version-15-hotfix/pr-42014
Your branch is ahead of 'origin/version-15-hotfix' by 1 commit.
  (use "git push" to publish your local commits)

You are currently cherry-picking commit 5844897c34.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   erpnext/crm/doctype/lead/lead.js

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[ruthra-kumar]

@Nihantra-Patel Could you resolve the conflicts?