Remove unused "install dependencies" step from Evergreen config

[GromNaN]

Build tasks on Ubuntu variants repeatedly fail with Hit exec timeout (10m0s), with the install dependencies step alone taking over 9 minutes:

[16:07:41] W: http://ppa.launchpad.net/git-core/ppa/... Key is stored in legacy trusted.gpg keyring
[16:15:36] Hit exec timeout (10m0s).
Command 'shell.exec' in function 'install dependencies' ... stopped early: context canceled
Finished command ... in 9m4.360644545s

The step runs drivers-evergreen-tools/.evergreen/install-dependencies.sh, which only does something on two platforms:

• linux-ubuntu*: apt-get update then apt-get -qqy -o DPkg::Lock::Timeout=-1 install awscli
• sunos*: pkgutil -i sasl_dev

Every other platform just echoes a message, which is why only Ubuntu hosts are affected.

Neither dependency is needed in this project:

• The aws CLI is never invoked anywhere in .evergreen/. S3 uploads and downloads use the native s3.put and s3.get commands, role assumption uses ec2.assume_role, and the only DET script we call that touches AWS, secrets_handling/setup-secrets.sh, uses the boto3 virtualenv instead of the CLI.
• There is no Solaris build variant.

The Ubuntu apt call passes DPkg::Lock::Timeout=-1, so it waits forever for the dpkg lock while unattended-upgrades runs on a freshly booted host. The task group sets setup_task_timeout_secs: 1800, but the global exec_timeout_secs: 600 covers the whole task including setup, so the task is killed before compiling anything.

This is not specific to one PHP version. Within build-all-php (max_hosts: 4), whichever task lands on a fresh host pays the lock wait, while the others find a warm apt cache.

This removes the function and its two call sites. evergreen validate passes and the generated config does not reference the function.

[GromNaN]

aws-cli might be necessary for mongodb-labs/drivers-evergreen-tools#840.

Answer: no, the implementation uses python+boto3.