Revert CA cert sub-directory processing in Linux entrypoints

.test/tests/java-ca-certificates-update/certs/README.md

@@ -4,7 +4,6 @@ These certificate/key pairs has been generated with
 $ openssl req -nodes -new -x509 -days 358000 -subj "/DC=Temurin/CN=DockerBuilder" -keyout certs/.dockerbuilder.key -out certs/.dockerbuilder.crt
 $ openssl req -nodes -new -x509 -days 358000 -subj "/DC=Temurin/CN=DockerBuilder2" -keyout certs/.dockerbuilder2.key -out certs/.dockerbuilder2.crt
 $ cat certs/.dockerbuilder.crt certs/.dockerbuilder2.crt > certs/multi-cert.crt
-$ openssl req -nodes -new -x509 -days 358000 -subj "/DC=Temurin/CN=DockerBuilder3" -keyout certs/subfolder/.dockerbuilder3.key -out certs/subfolder/.dockerbuilder3.crt
 ```
 
  and are only used for testing

.test/tests/java-ca-certificates-update/certs_symlink/README.md

@@ -4,7 +4,6 @@ These certificate/key pairs has been generated with
 $ openssl req -nodes -new -x509 -days 358000 -subj "/DC=Temurin/CN=DockerBuilder" -keyout certs/.dockerbuilder.key -out certs/.dockerbuilder.crt
 $ openssl req -nodes -new -x509 -days 358000 -subj "/DC=Temurin/CN=DockerBuilder2" -keyout certs/.dockerbuilder2.key -out certs/.dockerbuilder2.crt
 $ cat certs/.dockerbuilder.crt certs/.dockerbuilder2.crt > certs/multi-cert.crt
-$ openssl req -nodes -new -x509 -days 358000 -subj "/DC=Temurin/CN=DockerBuilder3" -keyout certs/subfolder/.dockerbuilder3.key -out certs/subfolder/.dockerbuilder3.crt
 ```
 
  and are only used for testing

.test/tests/java-ca-certificates-update/run.sh

@@ -10,7 +10,7 @@ CMD1=date
 
 # CMD2 in each run is to check for the `dockerbuilder` certificate in the Java keystore. Entrypoint exports $JRE_CACERTS_PATH to
 # point to the Java keystore.
-CMD2=(sh -c "keytool -list -keystore \"\$JRE_CACERTS_PATH\" -storepass changeit -alias dockerbuilder && keytool -list -keystore \"\$JRE_CACERTS_PATH\" -storepass changeit -alias dockerbuilder2 && keytool -list -keystore \"\$JRE_CACERTS_PATH\" -storepass changeit -alias dockerbuilder3")
+CMD2=(sh -c "keytool -list -keystore \"\$JRE_CACERTS_PATH\" -storepass changeit -alias dockerbuilder && keytool -list -keystore \"\$JRE_CACERTS_PATH\" -storepass changeit -alias dockerbuilder2")
 
 # CMD3 is looking for certificates with same CN, script appends the SHA-256 fingerprint to avoid alias conflict.
 # certs_duplicate_cn/cert1.crt will be imported first with alias dockerbuilder