Upgrade Gradle to 8.6 (#5533)

#### What type of PR is this?

/kind cleanup
/area core

#### What this PR does / why we need it:

Upgrade Gradle to 8.6 by executing command `./gradlew wrapper --gradle-version=8.6` according to <https://github.com/gradle/gradle/releases/tag/v8.6.0>.

#### Does this PR introduce a user-facing change?

```release-note
升级 Gradle 至 8.6
```

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,7 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
 networkTimeout=10000
+validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists

gradlew

@@ -83,10 +83,8 @@ done
 # This is normally unused
 # shellcheck disable=SC2034
 APP_BASE_NAME=${0##*/}
-APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
-
-# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
-DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
 
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD=maximum
@@ -133,26 +131,29 @@ location of your Java installation."
  fi
 else
  JAVACMD=java
- which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+ if ! command -v java >/dev/null 2>&1
+ then
+ die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
 
 Please set the JAVA_HOME variable in your environment to match the
 location of your Java installation."
+ fi
 fi
 
 # Increase the maximum file descriptors if we can.
 if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
  case $MAX_FD in #(
  max*)
  # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
- # shellcheck disable=SC3045
+ # shellcheck disable=SC2039,SC3045
  MAX_FD=$( ulimit -H -n ) ||
  warn "Could not query maximum file descriptor limit"
  esac
  case $MAX_FD in #(
  '' | soft) :;; #(
  *)
  # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
- # shellcheck disable=SC3045
+ # shellcheck disable=SC2039,SC3045
  ulimit -n "$MAX_FD" ||
  warn "Could not set maximum file descriptor limit to $MAX_FD"
  esac
@@ -197,11 +198,15 @@ if "$cygwin" || "$msys" ; then
  done
 fi
 
-# Collect all arguments for the java command;
-# * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
-# shell script including quotes and variable substitutions, so put them in
-# double quotes to make sure that they get re-expanded; and
-# * put everything else in single quotes, so that it's not re-expanded.
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+# * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+# and any embedded shellness will be escaped.
+# * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+# treated as '${Hostname}' itself on the command line.
 
 set -- \
  "-Dorg.gradle.appname=$APP_BASE_NAME" \