auth: skip zone cache refresh logic if disabled

[miodvallat]

Short description

No need to instantiate an UeberBackend only to have it do nothing.

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document, including the AI Policy, and added a "Signed-off-by" to my commits
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[coveralls]

Coverage Report for CI Build 25903193280

Warning

Build has drifted: This PR's base is out of sync with its target branch, so coverage data may include unrelated changes.
Quick fix: rebase this PR. Learn more →

Coverage increased (+4.1%) to 71.084%

Details

• Coverage increased (+4.1%) from the base build.
• Patch coverage: 10 uncovered changes across 1 file (19 of 29 lines covered, 65.52%).
• 275 coverage regressions across 16 files.

Uncovered Changes

File	Changed	Covered	%
pdns/auth-main.cc	29	19	65.52%

Coverage Regressions

275 previously-covered lines in 16 files lost coverage.

Top 10 Files by Coverage Loss	Lines Losing Coverage	Coverage
pdns/recursordist/rec-tcp.cc	143	24.64%
pdns/recursordist/lwres.cc	56	33.59%
pdns/recursordist/rec-tcpout.cc	13	25.68%
modules/pipebackend/coprocess.cc	11	47.26%
modules/pipebackend/pipebackend.cc	10	51.18%
pdns/recursordist/syncres.cc	9	77.14%
modules/ldapbackend/ldapbackend.cc	7	57.67%
pdns/dnsdistdist/dnsdist-tcp.cc	7	74.82%
pdns/recursordist/test-syncres_cc1.cc	6	80.16%
modules/ldapbackend/powerldap.cc	3	43.41%

---

Coverage Stats

Relevant Lines:	170073
Covered Lines:	132414
Line Coverage:	77.86%
Relevant Branches:	81078
Covered Branches:	46113
Branch Coverage:	56.87%
Branches in Coverage %:	Yes
Coverage Strength:	7332983.49 hits per line

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💛 - Coveralls

[mind04]

You can prevent the creation of one more, since there is also no need to initialize the zonecache when it is disabled. (somewhere around line 960)

[miodvallat]

Indeed! Good catch.