Optimize position-service (Java) Dockerfile

[mathieu-benoit]

Optimize position-service (Java) Dockerfile.

Continuity of #232, towards helping for this #231.

Note: this is moving from openjdk to eclipse-temurin as the recommended approach.

263MB have been saved with the uncompressed container image on disk:

REPOSITORY                               TAG        SIZE
position-service                         after      257MB
position-service                         before     521MB

On a security standpoint, by using eclipse-temurin:21-jre-alpine base image, this is also reducing the number of packages included in the container: with Syft, from 210 packages to 140 packages (70 packages included in the container image saved).

Which is consequently reducing the number of CVEs too, with Trivy, from 62 to 0:

┌────────────────────────────────────────┬────────┬─────────────────┐
│                 Target                 │  Type  │ Vulnerabilities │
├────────────────────────────────────────┼────────┼─────────────────┤
│ position-service:before (ubuntu 22.04) │ ubuntu │       62        │
├────────────────────────────────────────┼────────┼─────────────────┤
│ position-service:after (alpine 3.21.3) │ alpine │       0         │
├────────────────────────────────────────┼────────┼─────────────────┤

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