fix: reduce galaxy requirements check noise and de-duplicate path checks

[ksrp1984]

Description

Problem

On every Ansible task run, Semaphore probes a fixed set of candidate
requirements.yml locations and logs a line for each one that is missing:

No .../playbooks/collections/requirements.yml file found. Skip galaxy install process.
No .../playbooks/requirements.yml file found. Skip galaxy install process.
No .../collections/requirements.yml file found. Skip galaxy install process.
No .../requirements.yml file found. Skip galaxy install process.
No .../playbooks/roles/requirements.yml file found. Skip galaxy install process.
No .../playbooks/requirements.yml file found. Skip galaxy install process.
No .../roles/requirements.yml file found. Skip galaxy install process.
No .../requirements.yml file found. Skip galaxy install process.

That is up to 8 lines per run, and some are exact duplicates (the shared
<dir>/requirements.yml is probed once for roles and once for collections).
When collections/roles are managed globally and no requirements files are
expected in the repo, this is pure noise that hides the meaningful task output.

Related: #2982, #3111.

Behavior change — full algorithm

Requirements resolution is reworked into a collect → check → install flow.
Candidate paths are classified into two kinds, each with its own rule.

Search locations

Two base directories are searched:

• the playbook directory (GetPlaybookDir())
• the repository root (getRepoPath())

If these two resolve to the same directory (e.g. the playbook lives at the repo
root), it is searched once — duplicate base directories are removed up front.

Kind 1 — type-specific subdirectory files

<base>/roles/requirements.yml (roles only)
<base>/collections/requirements.yml (collections only)

Situation	Action
roles/ (or collections/) directory does not exist	Skip silently — nothing to install, no log
Directory exists, but requirements.yml is missing	Log one warning (likely a misconfiguration)
Directory exists and requirements.yml is present	Queue the file for installation

Kind 2 — shared root file

<base>/requirements.yml

This file may contain both roles: and collections: sections (the
canonical Ansible layout), so when present it is installed twice — once with
ansible-galaxy role install and once with ansible-galaxy collection install.

Situation	Action
At least one shared requirements.yml exists (any base dir)	Use the existing one(s); say nothing about missing locations
No shared requirements.yml exists in any base dir	Log a single message listing all paths that were searched

What gets de-duplicated vs. what is intentionally kept

• Removed: repeated checks/log lines for the same physical path, and the
  duplicate base directory when playbook dir == repo root.
• Kept (by design): a present shared requirements.yml is still processed
  for both roles and collections — this is not a duplicate, the two
  ansible-galaxy subcommands read different sections of the same file.

Before / after (example: repo with no requirements files, playbook at repo root)

Before — 8 lines (with duplicates):

No <root>/collections/requirements.yml file found. Skip galaxy install process.
No <root>/requirements.yml file found. Skip galaxy install process.
No <root>/collections/requirements.yml file found. Skip galaxy install process.
No <root>/requirements.yml file found. Skip galaxy install process.
No <root>/roles/requirements.yml file found. Skip galaxy install process.
No <root>/requirements.yml file found. Skip galaxy install process.
No <root>/roles/requirements.yml file found. Skip galaxy install process.
No <root>/requirements.yml file found. Skip galaxy install process.

After — 1 line:

No requirements.yml found. Skip galaxy install process. Searched:
  <root>/requirements.yml

(the roles/ and collections/ subdirectories don't exist, so they are skipped silently)

Implementation notes

• New resolveGalaxyRequirements() performs collect/check/logging and returns
  two slices of existing paths (roles, collections).
• installGalaxyRequirementsFile() no longer does existence checks or
  "not found" logging — it is only ever called with files that exist. Its md5
  change-detection ("has no changes. Skip…") is unchanged.
• installRolesRequirements() / installCollectionsRequirements() are kept and
  reused; they now take a pre-resolved []string of existing paths.
• Public InstallRequirements() signature is unchanged.
• No API changes (no Swagger/dredd impact).

Closes #2982
Closes #3111