fix: dont include dockerfilepath for hash calculation

[jLopezbarb]

Proposed changes

Fixes DEV-321

How to validate

1. Create the following okteto.yml:

services:
  nginx:
    image: nginx
    volumes: 
    - proxy:/etc/nginx/conf.d

2. Check that okteto build builds
3. Check that okteto build uses the smart build logic

CLI Quality Reminders 🔧

For both authors and reviewers:

• Scrutinize for potential regressions
• Ensure key automated tests are in place
• Build the CLI and test using the validation steps
• Assess Developer Experience impact (log messages, performances, etc)
• If too broad, consider breaking into smaller PRs
• Adhere to our code style and code review guidelines