chore: remove unused properties and schemas

[chadlwilson]

Description of Change

Some minor tidies

• removes unused properties default values
• deprecates the constants that referenced them (and some others without defaults); annotated with the ODC version they became dereferenced
• removes some old schema documents that are no longer used by or relevant to ODC itself (some have been moved to open-vulnerability-clients)

Have test cases been added to cover the new functionality?

N/A

[Copilot]

Pull request overview

This PR performs cleanup of Dependency-Check configuration artifacts by removing unused default properties, marking corresponding settings keys as deprecated, and deleting legacy schema resources that are no longer referenced by ODC.

Changes:

• Remove unused default entries from dependencycheck.properties (main + test resources).
• Deprecate no-longer-used settings keys in Settings.KEYS with forRemoval metadata.
• Remove legacy NVD/CPE schema documents and a stale commented-out NVD generation block from core/pom.xml.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
utils/src/test/resources/dependencycheck.properties	Drops unused proxy.disableSchemas and CPE defaults from utils test config.
utils/src/main/java/org/owasp/dependencycheck/utils/Settings.java	Deprecates unused settings constants (CPE, proxy schema disable, vfeed, downloader legacy keys).
core/src/test/resources/dependencycheck.properties	Drops unused proxy.disableSchemas and CPE defaults from core test config.
core/src/site/resources/images/readme.txt	Removes an obsolete readme file under site images.
core/src/main/resources/schema/external/nvd/nvd_cve_feed_json_1.1.schema	Deletes unused legacy NVD JSON schema resource.
core/src/main/resources/schema/external/nvd/cvss-v3.x.json	Deletes unused legacy CVSS v3 schema resource.
core/src/main/resources/schema/external/nvd/cvss-v2.0.json	Deletes unused legacy CVSS v2 schema resource.
core/src/main/resources/schema/external/nvd/CVE_JSON_4.0_min_1.1.schema	Deletes unused legacy CVE JSON schema resource.
core/src/main/resources/schema/external/cpe/cpe-dictionary_2.2.xsd	Deletes unused legacy CPE dictionary XSD resource.
core/src/main/resources/dependencycheck.properties	Drops unused proxy.disableSchemas and CPE defaults from main core config.
core/src/main/doc/schema/nvdcve/json/nvd_cve_feed_json_1.1.schema	Deletes unused legacy schema doc copy.
core/src/main/doc/schema/nvdcve/json/cvss-v3.x.json	Deletes unused legacy schema doc copy.
core/src/main/doc/schema/nvdcve/json/cvss-v2.0.json	Deletes unused legacy schema doc copy.
core/src/main/doc/schema/nvdcve/json/CVE_JSON_4.0_min_1.1.schema	Deletes unused legacy schema doc copy.
core/pom.xml	Removes a stale commented-out generate-nvd jsonschema2pojo execution block.

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