tools: Remove long-deprecated build_everything.py

[theotherjimmy]

Description

This needs to happen, because it removes a small disincentive to improving
the build system: verifying that this script still works. This PR removes
this file and the disincentive.

Pull request type

[ ] Fix
[x] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

[cmonr]

Is the reason that this file is long-deprecated because there are other tests that supercede it's functionality?

I took a look at its history, and found that the history is quite sparse. Is there any particular reason why other files that were a part of its original commit should not also be removed? (Ref: 0034ffb#diff-d1ccf7c14517be793178cf50b3203641)

[theotherjimmy]

@cmonr That commit is a big pile of unrelated features. It's long-deprecated because it does not have a call in travis, mbed-cli, or any other CI and it sees no maintenance.

[cmonr]

Starting a build to check something w/ the CI.
But also since this should be good but is still waiting on review.

/morph build

[mbed-ci]

Build : FAILURE

Build number : 1952
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/6823/

[cmonr]

Issues should be resolved.
/morph build

[mbed-ci]

Build : SUCCESS

Build number : 1956
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/6823/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

[mbed-ci]

Test : SUCCESS

Build number : 1772
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/6823/1772

[mbed-ci]

Exporter Build : FAILURE

Build number : 1606
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6823/

[theotherjimmy]

/morph export-build

[mbed-ci]

Exporter Build : SUCCESS

Build number : 1612
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/6823/

[0xc0170]

LGTM