Remove some IE11 support (Symbols) #12257

Job	Run time
tests / Basic Test	2m 12s
tests / Linting	1m 9s
tests / Type Checking (current version)	51s
tests / Perf script still works	3m 54s
tests / Type Checking (other supported versions) (5.4)	44s
tests / Type Checking (other supported versions) (5.3)	41s
tests / Type Checking (other supported versions) (5.6)	48s
tests / Type Checking (other supported versions) (5.7)	42s
tests / Type Checking (other supported versions) (5.2)	48s
tests / Type Checking (other supported versions) (5.5)	43s
tests / Type Checking (other supported versions) (5.8)	44s
tests / Type Checking (other supported versions) (5.9)	44s
tests / Blueprint Tests	1m 49s
tests / Browser Tests (Firefox)	2m 6s
tests / Node.js Tests	51s
tests / Smoke tests (Full Ember Apps) (classic-basics)	1m 40s
tests / Smoke tests (Full Ember Apps) (embroiderVite-basics)	2m 21s
tests / Production build	2m 18s
tests / Smoke tests (Full Ember Apps) (embroiderWebpack-basics)	1m 51s
tests / Smoke tests (Full Ember Apps) (classicUseModulesFeature-basics)	1m 58s
tests / All deprecations enabled	2m 15s
tests / Production build, with optional features	2m 11s
tests / Deprecations as errors, with optional features	2m 14s
tests / All deprecations enabled, with optional features	2m 18s
tests / Browserstack Tests (Safari, Edge)	17m 10s
tests / Deprecations as errors	2m 18s
Publish alpha from default branch	0s
Notify Discord	0s
Publish channel to s3	0s
	57m 20s

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