problem_report: reduce chunk size from 1 MB to 128 kB #1980

Job	Run time
linter	1m 46s
unit-and-integration (debian:bookworm-slim)	2m 56s
ruff	4s
unit-and-integration (debian:testing-slim)	3m 21s
unit-and-integration (ubuntu:noble)	3m 11s
unit-and-integration (ubuntu:oracular)	3m 13s
system-installed	31m 37s
unit-and-integration (ubuntu:plucky)	3m 43s
skip (ubuntu:noble)	2m 36s
system (ubuntu:noble)	32m 18s
skip (ubuntu:oracular)	2m 31s
system (ubuntu:oracular)	30m 27s
unit-and-integration-installed	3m 42s
skip (ubuntu:plucky)	2m 35s
system (ubuntu:plucky)	31m 47s
woke	5s
upload-to-codecov	11s
	2h 36m 3s

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