test: Improvements for TestClient

[philipphofmann]

Use the TestTransportAdapter in default init of TestClient, and only deleteOldEnvelopeItems in production.

The SentryProfilerSwiftTests keep failing, and the test logs show entries of calls in SentryHttpTransport and SentryFileManager.

https://github.com/getsentry/sentry-cocoa/actions/runs/4321925443/jobs/7545278715

#skip-changelog

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1216.15 ms	1243.49 ms	27.34 ms
Size	20.76 KiB	427.87 KiB	407.10 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
005bb4c	1237.38 ms	1255.54 ms	18.16 ms
7fb7afb	1230.12 ms	1251.04 ms	20.92 ms
b6ba04e	1217.45 ms	1248.92 ms	31.47 ms
7fb7afb	1227.73 ms	1243.16 ms	15.43 ms
cb2eefe	1222.04 ms	1243.04 ms	21.00 ms
4259afd	1222.12 ms	1249.74 ms	27.62 ms
f8fc36d	1226.31 ms	1247.80 ms	21.49 ms
7f691b5	1233.94 ms	1243.80 ms	9.86 ms
ecd9ecd	1204.67 ms	1226.46 ms	21.79 ms
0dedab7	1221.26 ms	1235.34 ms	14.08 ms

App size

Revision	Plain	With Sentry	Diff
005bb4c	20.76 KiB	419.70 KiB	398.94 KiB
7fb7afb	20.76 KiB	419.70 KiB	398.94 KiB
b6ba04e	20.76 KiB	414.45 KiB	393.69 KiB
7fb7afb	20.76 KiB	419.70 KiB	398.94 KiB
cb2eefe	20.76 KiB	419.62 KiB	398.86 KiB
4259afd	20.76 KiB	419.70 KiB	398.94 KiB
f8fc36d	20.76 KiB	419.70 KiB	398.94 KiB
7f691b5	20.76 KiB	420.55 KiB	399.79 KiB
ecd9ecd	20.76 KiB	420.23 KiB	399.47 KiB
0dedab7	20.76 KiB	420.00 KiB	399.24 KiB

Previous results on branch: test/use-test-transpart-adapter-in-test-client

Startup times

Revision	Plain	With Sentry	Diff
542210a	1242.80 ms	1263.44 ms	20.64 ms

App size

Revision	Plain	With Sentry	Diff
542210a	20.76 KiB	427.79 KiB	407.03 KiB