Merge pull request grpc#21979 from apolcyn/bump_to_pre2

Bump 1.27.x branch to 1.27.2

Merge pull request grpc#21928 from apolcyn/bump_version_to_27_1

Bump version on 1.27.x branch to 1.27.1

Merge pull request grpc#21887 from apolcyn/backport_revert

Backport grpc#21721: Revert "grpclb stabilization"

Merge pull request grpc#21800 from apolcyn/bump_tp_pre2

Bump 1.27.x branch to pre2

Merge pull request grpc#21764 from lidizheng/patch-time-out-1.27

[v1.27.x Patch] Double the time limit for linux extra artifacts build

Merge pull request grpc#21502 from gnossen/v1.26.x

Backport grpc#21487 to v1.26.x.

Merge pull request grpc#21358 from gnossen/bump_1_26_x_version

Bump 1.26.x version to 1.26.0-pre1

Merge pull request grpc#20948 from yashykt/v1.25.0-bump

Bump version to v1.25.0

Merge pull request grpc#20776 from yashykt/v1.25.x_update_to_pre1

Bump version to v1.25.0-pre1

Merge pull request grpc#20728 from veblush/v1.24-manylinux2010

Backport grpc#20616 grpc#20673