Fix `tf_metrics_reconcile_last_timestamp` scientific notation

Miroslav Vadkertirequested to merge
mvadkert/nucleus:fix-metrics-timestamp-precision into main

The :g format specifier caused Unix timestamps to render in scientific notation (e.g. 1.77886e+09 instead of 1778860000), losing precision for Prometheus consumers. Use :.0f to preserve full integer representation.

Assisted-by: Claude Code Signed-off-by: Miroslav Vadkerti mvadkert@redhat.com

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