Periodical stalls in LLViewerMediaImpl::update

[akleshchev]

navigateInternal has detailed logging which is usefull when it's being used as 'one off', but causes up to 40ms stalls when viewer suspends and unuspends media during an update.

Unfortunately our logging system isn't cheap, so just avoid logging this data on periodical basis.

Test plan

• Look at the Frame jitter while viewing Media on a Prim.
• Verify Frame jitter is not worse.

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[akleshchev]

Small change for better proiling and less spammy media logging. Should make framerate a bit more stable.

[Dan-Linden]

Passed QA.
Verified on Second Life Release 26.3.0.27582727395 on Win11/OSX in the scope of secondlife/iqa#660

On a relatively modern system, it's not noticeably better, but it's not worse.
On a 12 year old potato laptop running win10, the jitter is noticeably less.

Tested at https://maps.secondlife.com/secondlife/Danger!%20Danger!/58/5/37 facing South, looking at 4 media prims (news.google.com, lindenlab.com, secondlife.com, imdb.com)