trace2: tolerate failed timestamp formatting #29029

Job	Run time
config	9s
fuzz smoke test	51s
win build	1m 40s
win+Meson build	2m 12s
rust-analysis	1m 52s
documentation	6m 20s
osx-clang (macos-14)	24s
sparse	2m 14s
osx-meson (macos-14)	26s
static-analysis	5m 15s
osx-reftable (macos-14)	30s
linux-asan-ubsan (ubuntu:rolling)	2m 4s
linux-breaking-changes (ubuntu:rolling)	1m 37s
osx-gcc (macos-14)	29s
linux-reftable (ubuntu:rolling)	1m 50s
linux-meson (ubuntu:rolling)	1m 28s
fedora-breaking-changes-meson (fedora:latest)	1m 35s
linux-sha256 (ubuntu:rolling)	1m 58s
linux-leaks (ubuntu:rolling)	1m 21s
linux-reftable-leaks (ubuntu:rolling)	1m 45s
almalinux-8 (almalinux:8)	1m 25s
debian-11 (debian:11)	1m 19s
linux-musl-meson (alpine:latest)	35s
linux-TEST-vars (ubuntu:20.04)	1m 36s
linux32 (i386/ubuntu:20.04)	1m 40s
win+VS test	-1s
win+VS build	-1s
win test	0s
win+Meson test	0s
	42m 33s

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