pagectl: skip metadata file in pagectl draw-timeline

[jcsp]

Problem

Running pagectl draw-timeline on a pageserver directory wasn't working out of the box because it trips up on the metadata file.

Summary of changes

Just ignore the metadata file in the list of input files passed to draw-timeline.

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

1264 tests run: 1215 passed, 0 failed, 49 skipped (full report)

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[jcsp]

e2e tests failed with a connection error to docker.io