Revert "mariadb-connector-c: upgraded package to upstream"

This reverts commit f5fa801641bac802e453716dfb22fbdc93fcaaac.

Reason for revert: Remove extra copy.
Fixes breakage noticed in https://ci.chromium.org/p/chromeos/builders/general/Try/b8836007344563817057?

Original change's description:
> mariadb-connector-c: upgraded package to upstream
>
> Upgraded dev-db/mariadb-connector-c to version 3.1.13 on amd64
>
> BUG=b:199174229
> TEST=sudo emerge dev-db/mariadb-connector-c
>
> Change-Id: I2b592915a5e310858090cfcc90d893be928b8d66
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3147255
> Tested-by: Allen Webb <allenwebb@google.com>
> Reviewed-by: Jordan R Abrahams <ajordanr@google.com>
> Reviewed-by: Christopher Di Bella <cjdb@google.com>
> Commit-Queue: Allen Webb <allenwebb@google.com>

Bug: b:199174229
Change-Id: Ic7020ca6252152cb103b193610a9b304ccfafac7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/3163434
Auto-Submit: Manoj Gupta <manojgupta@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
7 files changed