Since support for the commandName attribute was removed from the
implementation of FormTag in Spring Framework 5.0, the presence of the
commandName attribute in the spring-form.tld file is no longer valid
and can lead one to assume that the commandName attribute is still
supported -- for example when using code completion in a JSP editor.
This commit therefore removes the obsolete commandName attribute in
spring-form.tld.
Closes gh-26337