Cherry-pick of PR #19535 to 7.x branch. Original message:

What does this PR do?

ATM when we run go get goimports on CI it modifies go.mod to include latest (daily) version of x/tools
this causes lint to break and results in PR bringing x/tools version up to date in PR fixes

Why is it important?

To avoid failures like this:

diff --git a/go.mod b/go.mod
index 552b28cbb4..f4867e4d91 100644
--- a/go.mod
+++ b/go.mod
@@ -163,7 +163,7 @@ require (
        golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5
        golang.org/x/text v0.3.2
        golang.org/x/time v0.0.0-20191024005414-555d28b269f0
-       golang.org/x/tools v0.0.0-20200626171337-aa94e735be7f
+       golang.org/x/tools v0.0.0-20200630154851-b2d8b0336632
        google.golang.org/api v0.15.0
        google.golang.org/genproto v0.0.0-20191230161307-f3c370f40bfb
        google.golang.org/grpc v1.29.1

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.