Fix crash with RenderDiagnosticsPlugin on mac

[akimakinai]

Objective

• Fixes log diagnostics example crash on mac due to RenderDiagnosticsPlugin #21167
  (happens with trace_tracy feature too, as it adds the plugin automatically)
• There are some uses of time_span inside passes, which go around the check for TIMESTAMP_QUERY_INSIDE_PASSES feature (unsupported on Apple GPU).
  introduced in Record render diagnostics for all engine passes #19191

Solution

• They look like just typos (all in let pass_span = time_span form), so replaced with pass_span.

There's an occurence of this pattern in meshlet/visibility_buffer_raster_node.rs, but it's the variable name that seems incorrect in this case. I renamed it instead.

Testing

• Running log_diagnostics example no longer crashes on Mac.

[janhohenheim]

Pinging @jf908 who introduced the relevant lines :)

[akimakinai]

Probably time_span should be changed to take encoder rather than being generic over encoder/pass if my understanding above is correct. (As a separate PR)