AT-11223: Update ACM get certificate error for the Edge endpoint type

[rddimon]

https://amplify-education.atlassian.net/browse/AT-11223

Fixes #509

Description of Issue Fixed
Updated ACM get certificate error message for the EDGE endpoint type

Changes proposed in this pull request:

• Error message update

[sonarcloud]

Quality Gate passed

Issues
0 New issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[amplify-self-hosted-runners]

Check Name	Conclusion	Summary	Output
SonarCloud Code Analysis	success	Quality Gate passed	output
Codacy Static Code Analysis	success	Your pull request is up to standards!	output
Mend Security Check	success	Security Report	output
Mend License Check	success	License Report	output
test (14.x)	success	test (14.x)	output
test (16.x)	success	test (16.x)	output
test (18.x)	success	test (18.x)	output
test (20.x)	success	test (20.x)	output