[TestOptimization] Catch IOException on the Git folder discovery (#7658)

## Summary of changes

This PR adds another exception catch but for the IOException.

## Reason for change

This exception appears on a customer:
```
System.IO.IOException
     at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
     at System.IO.FileSystemEnumerableIterator`1.CommonInit()
     at System.IO.FileSystemEnumerableIterator`1..ctor(String path, String originalUserPath, String searchPattern, SearchOption searchOption, SearchResultHandler`1 resultHandler, Boolean checkHost)
     at System.IO.DirectoryInfo.InternalGetDirectories(String searchPattern, SearchOption searchOption)
     at Datadog.Trace.Ci.CIEnvironment.GitInfo.GetParentGitFolder(String innerFolder)
     at Datadog.Trace.Ci.CIEnvironment.GitInfo.GetCurrent()
     at Datadog.Trace.Ci.CIEnvironment.CIEnvironmentValues.ReloadEnvironmentData()
     at Datadog.Trace.Ci.CIEnvironment.CIEnvironmentValues.Create()
     at System.Lazy`1.CreateValue()
     at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
     at System.Lazy`1.get_Value()
     at Datadog.Trace.Ci.TestOptimization.<>c.<get_Instance>b__16_0()
     at System.Threading.LazyInitializer.EnsureInitializedCore[T](T& target, Func`1 valueFactory)
     at Datadog.Trace.SpanContext..ctor(TraceId traceId, String serviceName)
     at Datadog.Trace.SpanContext..ctor(ISpanContext parent, TraceContext traceContext, String serviceName, TraceId traceId, UInt64 spanId, String rawTraceId, String rawSpanId, Boolean isRemote)
     at Datadog.Trace.Tracer.CreateSpanContext(ISpanContext parent, String serviceName, TraceId traceId, UInt64 spanId, String rawTraceId, String rawSpanId, Boolean addToTraceContext, IEnumerable`1 links)
     at Datadog.Trace.Tracer.StartSpan(String operationName, ITags tags, ISpanContext parent, String serviceName, Nullable`1 startTime, TraceId traceId, UInt64 spanId, String rawTraceId, String rawSpanId, Boolean
  addToTraceContext, IEnumerable`1 links)
     at Datadog.Trace.ClrProfiler.ScopeFactory.CreateInactiveOutboundHttpSpan(Tracer tracer, String httpMethod, Uri requestUri, IntegrationId integrationId, HttpTags& tags, TraceId traceId, UInt64 spanId, Nullable`1
  startTime, Boolean addToTraceContext)
```

## Implementation details

a single new catch of the existing try/catch blocks

## Test coverage

## Other details
<!-- Fixes #{issue} -->


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Author: tonyredondo

tracer/src/Datadog.Trace/Ci/CiEnvironment/GitInfo.cs

@@ -192,6 +192,11 @@ public static IGitInfo GetCurrent()
                 Log.Warning(ex, "Get directories failed with DirectoryNotFoundException");
                 return null;
             }
+            catch (IOException ex)
+            {
+                Log.Warning(ex, "Get directories failed with IOException");
+                return null;
+            }
             catch (UnauthorizedAccessException ex)
             {
                 Log.Warning(ex, "Get directories failed with UnauthorizedAccessException");