Add null check when a view does not match an instrument

[alanwest]

Fixes #3283

Bug was causing superfluous warnings in diagnostic logs when an instrument didn't match a view config. For example:

2022-05-17T19:29:28.8189110Z:View Configuration ignored for Instrument '{0}', Meter '{1}'. Reason: '{2}'. Measurements from the instrument will use default configuration for Aggregation. Suggested action: '{3}'{http.client.duration}{OpenTelemetry.Instrumentation.Http}{Object reference not set to an instance of an object.}{Fix the view configuration.}

[reyang]

Need a changelog entry?

[codecov]

Codecov Report

Merging #3285 (c405a04) into main (a383463) will increase coverage by 0.20%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #3285      +/-   ##
==========================================
+ Coverage   85.39%   85.60%   +0.20%     
==========================================
  Files         255      263       +8     
  Lines        9355     9487     +132     
==========================================
+ Hits         7989     8121     +132     
  Misses       1366     1366              

Impacted Files	Coverage Δ
src/OpenTelemetry/Metrics/MeterProviderSdk.cs	89.50% <100.00%> (ø)
...lemetry/Internal/SelfDiagnosticsConfigRefresher.cs	86.53% <0.00%> (-1.93%)	⬇️
...nTelemetry/Internal/OpenTelemetrySdkEventSource.cs	74.13% <0.00%> (-1.73%)	⬇️
...entation.AspNet/TracerProviderBuilderExtensions.cs	100.00% <0.00%> (ø)
...rumentation.AspNet/AspNetInstrumentationOptions.cs	100.00% <0.00%> (ø)
...Implementation/AspNetInstrumentationEventSource.cs	76.92% <0.00%> (ø)
...ry.Instrumentation.AspNet/AspNetInstrumentation.cs	100.00% <0.00%> (ø)
...nTelemetry.Instrumentation.AspNet/AspNetMetrics.cs	100.00% <0.00%> (ø)
...mentation.AspNet/MeterProviderBuilderExtensions.cs	100.00% <0.00%> (ø)
...ion.AspNet/Implementation/HttpInMetricsListener.cs	100.00% <0.00%> (ø)
... and 6 more