adb: make the push summary fit in 80 columns.

Elide $ANDROID_PRODUCT_OUT for a large saving:

  /data/: 2 files pushed. 734 files skipped. 6.5 MB/s (830776 bytes in 0.122s)
  /product/: 0 files pushed. 357 files skipped.
  /system/: 7 files pushed. 2638 files s...d. 16.3 MB/s (3785511 bytes in 0.221s)
  /system_ext/: 1 file pushed. 90 files ...d. 13.2 MB/s (1152016 bytes in 0.084s)
  /vendor/: 0 files pushed. 200 files skipped.

And drop the repeated "files" when talking about how many were skipped
for a small saving:

  /data/: 2 files pushed, 734 skipped. 6.4 MB/s (830776 bytes in 0.124s)
  /product/: 0 files pushed, 357 skipped.
  /system/: 7 files pushed, 2638 skipped. 13.8 MB/s (3785511 bytes in 0.262s)
  /system_ext/: 1 file pushed, 90 skipped. 12.2 MB/s (1152016 bytes in 0.090s)
  /vendor/: 0 files pushed, 200 skipped.

Bug: http://b/131717844
Test: adb sync
Change-Id: I9d24df49498211bc2b8dcebcc6d8bd557da214c1