feat(traces): updated btn copy (#71357)

**Before:**
![Screenshot 2024-05-22 at 9 30
03 AM](https://github.com/getsentry/sentry/assets/4830259/d4efffbb-0615-4b34-a9d3-377f81c242ea)

**After:**
![Screenshot 2024-05-22 at 9 29
43 AM](https://github.com/getsentry/sentry/assets/4830259/00d07670-c625-443c-b9c2-90ded11918ab)

static/app/views/performance/traces/tracesSearchBar.tsx

@@ -69,7 +69,7 @@ export function TracesSearchBar({
           size="sm"
           onClick={() => handleSearch(localQueries.length, '')}
         >
-          {t('Add Span')}
+          {t('Add Span Condition')}
         </Button>
       ) : null}
     </TraceSearchBarsContainer>