[BUGFIX release] Remove use of `this.element` in `component-test` and `helper-test` blueprints #7413

Job	Run time
Type Checking (current version)	1m 7s
Linting	1m 41s
Debug and Prebuilt (All Tests by Package + Canary Features)	5m 5s
Type Checking (other supported versions) (4.9)	1m 50s
Type Checking (other supported versions) (5.0)	1m 44s
Type Checking (other supported versions) (next)	1m 49s
Blueprint Tests	3m 57s
Production (All Tests + Canary Features)	7m 43s
Browserstack Tests (Safari, Edge)	3m 0s
Browser Tests (Firefox)	2m 55s
Extend Prototypes	4m 26s
Node.js Tests	1m 25s
Production (All Tests + Canary Features with Debug Render Tree)	6m 50s
Smoke tests (Full Ember Apps)	2m 57s
Publish channel to s3	0s
Deploy tags to npm	0s
Notify Discord	0s
Publish alpha from default branch	0s
	46m 29s

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