Clean-up: removed unused symbol in full_ctor.cpp

[oleksandr-pavlyk]

Remove using statement adding an unused qualifier to the namespace.

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/1313/index.html

[coveralls]

coverage: 84.776%. remained the same when pulling 2f9ea6f on clean-up-full-ctor-cpp into 1cc45e4 on master.

[github-actions]

Array API standard conformance tests for dpctl=0.14.6dev0=py310h7bf5fec_59 ran successfully.
Passed: 593
Failed: 407
Skipped: 119

[ndgrigorian]

LGTM, nice catch

[github-actions]

Deleted rendered PR docs from intelpython.github.com/dpctl, latest should be updated shortly. 🤞

[github-actions]

Array API standard conformance tests for dpctl=0.14.6dev0=py310h7bf5fec_67 ran successfully.
Passed: 594
Failed: 406
Skipped: 119