Do not cache generateLicenseReport tasks

[alexander-yevsyukov]

What

Opts the per-project generateLicenseReport task out of the Gradle build cache
via outputs.doNotCacheIf().

Why

Gradle Doctor flags every one of these tasks as
slower from cache.
From a build of core-jvm-compiler:

| The following operations were slower to pull from the cache than to rerun:  |
| :routing-tests:generateLicenseReport                                        |
| :grpc:generateLicenseReport                                                 |
| :message-group:generateLicenseReport                                        |
| ... (16 tasks in total)                                                     |
| Consider disabling caching them.                                            |

The task only re-renders already resolved dependency metadata into a small
Markdown file. That costs less than hashing the inputs, looking the entry up,
and unpacking it — so the cache is a net loss here.

Notes for the reviewer

• Up-to-date checks are unaffected. doNotCacheIf suppresses only
  build-cache store/load, not incremental skipping, so an unchanged project
  still skips the task entirely.
• The neighbouring comment about the projectVersion input was reworded: it
  previously argued in terms of "restorable from the build cache", which is no
  longer the failure mode. The input itself stays — it still drives the
  up-to-date check.
• doNotCacheIf was chosen over cacheIf { false } because the task is already
  annotated @CacheableTask by the jk1 plugin, so this is an opt-out. The
  reason string surfaces in --info output and build scans.
• JS projects are covered too. io.spine.gradle.javascript.task.licenseReport()
  configures the same task instance (adding npmLicenseReport as a finalizer)
  rather than registering its own, so it inherits the opt-out.

Testing

./gradlew -p buildSrc build passes, including DependencyReportOutputTest.
The config root has no build lifecycle task, so buildSrc is the
compilation unit here.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR opts the per-project generateLicenseReport task out of Gradle’s build cache to avoid cache overhead for a task that is cheaper to rerun than to restore, while preserving up-to-date behavior via explicit task inputs.

Changes:

• Disabled build-cache store/load for generateLicenseReport via outputs.doNotCacheIf(...).
• Reworded the projectVersion input comment to focus on up-to-date behavior rather than cache restore.
• Minor refactor to use imported Paths.relativePath / Paths.outputFilename constants.