Partial or multiple env variables not being evaluated in plugin parameters

**Logstash information**:

1. Logstash version 8.9.0
2. Logstash installation source: docker
3. How is Logstash being run: docker

**Plugins installed**: (`bin/logstash-plugin list --verbose`)
logstash-codec-avro (3.4.0)
logstash-codec-cef (6.2.7)
logstash-codec-collectd (3.1.0)
logstash-codec-dots (3.0.6)
logstash-codec-edn (3.1.0)
logstash-codec-edn_lines (3.1.0)
logstash-codec-es_bulk (3.1.0)
logstash-codec-fluent (3.4.2)
logstash-codec-graphite (3.0.6)
logstash-codec-json (3.1.1)
logstash-codec-json_lines (3.1.0)
logstash-codec-line (3.1.1)
logstash-codec-msgpack (3.1.0)
logstash-codec-multiline (3.1.1)
logstash-codec-netflow (4.3.0)
logstash-codec-plain (3.1.0)
logstash-codec-rubydebug (3.1.0)
logstash-filter-aggregate (2.10.0)
logstash-filter-anonymize (3.0.7)
logstash-filter-cidr (3.1.3)
logstash-filter-clone (4.2.0)
logstash-filter-csv (3.1.1)
logstash-filter-date (3.1.15)
logstash-filter-de_dot (1.0.4)
logstash-filter-dissect (1.2.5)
logstash-filter-dns (3.2.0)
logstash-filter-drop (3.0.5)
logstash-filter-elasticsearch (3.15.1)
logstash-filter-fingerprint (3.4.3)
logstash-filter-geoip (7.2.13)
logstash-filter-grok (4.4.3)
logstash-filter-http (1.4.3)
logstash-filter-json (3.2.0)
logstash-filter-kv (4.7.0)
logstash-filter-memcached (1.2.0)
logstash-filter-metrics (4.0.7)
logstash-filter-mutate (3.5.7)
logstash-filter-prune (3.0.4)
logstash-filter-ruby (3.1.8)
logstash-filter-sleep (3.0.7)
logstash-filter-split (3.1.8)
logstash-filter-syslog_pri (3.2.0)
logstash-filter-throttle (4.0.4)
logstash-filter-translate (3.4.2)
logstash-filter-truncate (1.0.6)
logstash-filter-urldecode (3.0.6)
logstash-filter-useragent (3.3.4)
logstash-filter-uuid (3.0.5)
logstash-filter-xml (4.2.0)
logstash-input-azure_event_hubs (1.4.5)
logstash-input-beats (6.6.3)
└── logstash-input-elastic_agent (alias)
logstash-input-couchdb_changes (3.1.6)
logstash-input-dead_letter_queue (2.0.0)
logstash-input-elasticsearch (4.17.2)
logstash-input-exec (3.6.0)
logstash-input-file (4.4.4)
logstash-input-ganglia (3.1.4)
logstash-input-gelf (3.3.2)
logstash-input-generator (3.1.0)
logstash-input-graphite (3.0.6)
logstash-input-heartbeat (3.1.1)
logstash-input-http (3.7.2)
logstash-input-http_poller (5.4.0)
logstash-input-imap (3.2.0)
logstash-input-jms (3.2.2)
logstash-input-pipe (3.1.0)
logstash-input-redis (3.7.0)
logstash-input-rest_client (1.0.0)
logstash-input-snmp (1.3.2)
logstash-input-snmptrap (3.1.0)
logstash-input-stdin (3.4.0)
logstash-input-syslog (3.6.0)
logstash-input-tcp (6.3.5)
logstash-input-twitter (4.1.0)
logstash-input-udp (3.5.0)
logstash-input-unix (3.1.2)
logstash-integration-aws (7.1.4)
├── logstash-codec-cloudfront
├── logstash-codec-cloudtrail
├── logstash-input-cloudwatch
├── logstash-input-s3
├── logstash-input-sqs
├── logstash-output-cloudwatch
├── logstash-output-s3
├── logstash-output-sns
└── logstash-output-sqs
logstash-integration-elastic_enterprise_search (2.2.1)
├── logstash-output-elastic_app_search
└── logstash-output-elastic_workplace_search
logstash-integration-jdbc (5.4.4)
├── logstash-input-jdbc
├── logstash-filter-jdbc_streaming
└── logstash-filter-jdbc_static
logstash-integration-kafka (11.2.1)
├── logstash-input-kafka
└── logstash-output-kafka
logstash-integration-rabbitmq (7.3.3)
├── logstash-input-rabbitmq
└── logstash-output-rabbitmq
logstash-output-csv (3.0.9)
logstash-output-elasticsearch (11.15.9)
logstash-output-email (4.1.2)
logstash-output-file (4.3.0)
logstash-output-graphite (3.1.6)
logstash-output-http (5.5.0)
logstash-output-lumberjack (3.1.9)
logstash-output-nagios (3.0.6)
logstash-output-null (3.0.5)
logstash-output-opensearch (2.0.1)
logstash-output-pipe (3.0.6)
logstash-output-redis (5.0.0)
logstash-output-stdout (3.1.4)
logstash-output-tcp (6.1.2)
logstash-output-udp (3.2.0)
logstash-output-webhdfs (3.0.6)
logstash-patterns-core (4.3.4)

**JVM** (e.g. `java -version`):

If the affected version of Logstash is 7.9 (or earlier), or if it is NOT using the bundled JDK or using the 'no-jdk' version in 7.10 (or higher), please provide the following information:

1. JVM version: bundled JDK
2. JVM installation source (e.g. from the Operating System's package manager, from source, etc).
3. Value of the `LS_JAVA_HOME` environment variable if set.

**OS version** (`uname -a` if on a Unix-like system):
Windows 11 with WSL

**Description of the problem including expected versus actual behavior**:
When using multiple environment variables or an env variable together with any string value in Java plugin parameters, env variables will not evaluated.

Eg:

input {
java_plugin {
url => 'https://localhost:${ENV_VAR}'

${ENV_VAR} will not be evaluated, and no error (if the env variable is not assigned) will be thrown either.

**Steps to reproduce**:

Start any pipeline with config that contains multiple env variables.

**Provide logs (if relevant)**:

Start by reproducing the issue with a Java plugin configuration that combines multiple environment variables or an environment variable with literal text. Trace the environment-variable evaluation used for plugin parameters; done means the variables are evaluated consistently and the behavior for an unset variable is covered.

Written by the indexing model from the issue text.