Revert "Refactor AnalyzerConfig to use Timestamps instead of microseconds."

This reverts commit 43fb16921b29ecd3a2d87876dda75c575e05f66a.

Reason for revert: New type breaks downstream projects.

Original change's description:
> Refactor AnalyzerConfig to use Timestamps instead of microseconds.
>
> Add optional offset-to-UTC parameter to output. This allows aligning
> the x-axis in the generated charts to other UTC-based logs.
>
> Bug: b/215140373
> Change-Id: I65bcd295718acbb8c94e363907c1abc458067bfd
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/250203
> Reviewed-by: Kristoffer Erlandsson <kerl@google.com>
> Commit-Queue: Björn Terelius <terelius@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#35992}

TBR=terelius@webrtc.org,kerl@google.com,webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: If4f2330b9731f26a0e55c9ce9a500322a111b783
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: b/215140373
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/251691
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Evan Shrubsole <eshr@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Christoffer Jansson <jansson@google.com>
Cr-Commit-Position: refs/heads/main@{#35994}