[BUGFIX lts] Restore `{{this.attrs.foo}}` deprecation #8695

Job	Run time
Type Checking (current version)	47s
Linting	1m 9s
Debug and Prebuilt (All Tests by Package + Canary Features)	3m 38s
Type Checking (other supported versions) (4.9)	1m 3s
Type Checking (other supported versions) (5.0)	1m 11s
Type Checking (other supported versions) (5.1)	1m 5s
Type Checking (other supported versions) (5.2)	57s
Type Checking (other supported versions) (5.3)	1m 0s
Blueprint Tests	7m 50s
Browserstack Tests (Safari, Edge)	2m 4s
Smoke tests (Full Ember Apps)	1m 37s
Debug and Prebuilt (All Tests by Package + Canary Features) with Deprecations as Errors	3m 4s
Debug and Prebuilt (All Tests by Package + Canary Features) with all Deprecations enabled	3m 13s
Production (All Tests + Canary Features with Debug Render Tree)	3m 8s
Production (All Tests + Canary Features)	3m 1s
Browser Tests (Firefox)	1m 39s
Extend Prototypes	2m 35s
Node.js Tests	56s
Deploy tags to npm	0s
Publish alpha from default branch	0s
Publish channel to s3	0s
Notify Discord	0s
	39m 57s

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