Fix mis-scaled signals for subject 015: divide by 1e6 (part 10/33 of full fix for subjects 004,005,008-035,058-060).

sourcedata/braindecode/dataset.zarr/recording_15/data/c/0/0/0

@@ -1,3 +1,3 @@
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-oid sha256:7170b2141b1b46194ba1df94053834a37efd3c6d0381c5b16b18bac141ff713d
-size 18538700
+oid sha256:aaaee24e1934c9bf39cd2af1ed69c0d352c009c5b3469cf07f72fc3aedc1f62e
+size 18535026

sourcedata/braindecode/dataset.zarr/recording_15/data/c/1/0/0

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:9e8235d869be6ba41aa8791da284dbf2c7c243530878194e220984d064675811
-size 11599658
+oid sha256:8e68b4a30d81df84bf99157094fe3f92428e1920ae34ec877831fe1dca6e6788
+size 11597127