Annotate the Sync IPCs differently in IPC tracks

In addition to the IPC markers, we also have "Sync IPC" tracing markers. But we actually also record them with the IPC messages feature, so they are technically marker duplications once we have the "ipcmessages" feature on by default. We can probably remove the "Sync IPC" tracing markers later.

But also, sync IPCs are usually sources of bottlenecks and we should treat them differently. That's why, we should annotate the sync IPCs in a different way, so they can be more visible to our users.

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-524)