fix: perform autoreg waiting when performing standard autoreg

[ptoscano]

The initial delay when performing the standard autoregistration used to
be done directly in rhsmcertd (the C daemon). When the anonymous
autoregistration was implemented, since it has to start immediately,
that delay in rhsmcertd was dropped in favour of doing it "inline"
during the autoregistration. The waiting was added only during the
anonymous autoregistration flow and not during the standard
autoregistration.

Hence, add the autoregistration wait/delay before performing the
standard autoregistration, restoring the previous behaviour.

There is a small commit factorizing the code to an helper function.

[github-actions]

Coverage (computed on Fedora latest) •

File	Stmts	Miss	Cover	Missing
subscription_manager/scripts
rhsmcertd_worker.py	192	122	36%	42–45, 87, 92–95, 100–101, 106–109, 149, 169–171, 173–175, 179, 188, 190, 194–196, 200, 203–206, 209, 212–213, 219–221, 223–227, 229–230, 240, 242, 244–245, 262, 265–266, 269, 272, 274–275, 278–280, 283, 287–294, 298–300, 303, 307–309, 311, 317, 319, 321–324, 326–328, 330–331, 335, 337, 339, 341, 343–345, 347, 349–350, 352–356, 362–363, 367, 369, 373, 375–377, 387–390, 395–400, 404
TOTAL	17819	4512	74%

Tests	Skipped	Failures	Errors	Time
2489	14 💤	0 ❌	0 🔥	35.003s ⏱️

[m-horky]

LGTM