Remove additional grib test file

Author: SebastianThomas

grib/src/test/data/index/icon-ch2-eps-202606230000-0-poacsnc-ctrl.grib2

@@ -15,8 +15,8 @@
 import org.junit.runners.JUnit4;
 
 /**
- * Test data from github issue https://github.com/Unidata/netcdf-java/issues/41
- * Data was used to create a .gbx9 file for testing.
+ * Test data from Meteo Swiss CH2 https://data.geo.admin.ch/browser/#/collections/ch.meteoschweiz.ogd-forecasting-icon-ch2?.language=en
+ * Pollen Grasses Data (POACsnc parameter) was used to create a .gbx9 file for testing.
  * <p>
  * PDS (Secton 4) output from ecCodes grib_dump at the end of the file, uses as a basis for
  * testing PDS (Secton 4) parsing