fix: template callable is now correctly registered when using custom env #4160

Job	Run time
mypy	2m 15s
pyright	2m 0s
slotscheck	1m 32s
Test server integration (uvicorn<0.27.0)	1m 44s
Test server integration (uvicorn>=0.27.0)	1m 29s
Test Minimal Application with Base Dependencies	5m 33s
Test Minimal Pydantic 1 application	1m 41s
test-platform-compat	0s
validate	24s
test (3.10) / test	2m 51s
test (3.11) / test	2m 35s
test (3.12) / test	3m 53s
test (3.8) / test	3m 51s
test (3.9) / test	3m 2s
build-docs	3m 14s
codeql	2m 56s
upload-test-coverage	17s
sonar	0s
	39m 17s

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