Fix error string mapping to HTTP response code to ignore case

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Fix volume test using "find" to properly call find with /hello path

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Merge pull request #8733 from estesp/error-string-http-status-fix

Fix error string mapping to HTTP response code to ignore case