fix the bug that cannot detect multi qrcode when use_nn_detector is false

[bit1002lst]

A new PR based on the top of 4.x and fix the conflicts
related issus #3343

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

[bit1002lst]

@asmorkalov

[bit1002lst]

Why the status of this PR is pending？

[bit1002lst]

@asmorkalov Hello，can you tell me why my pr is pending on buildbot？thanks

[asmorkalov]

"opencv:4.x from bit1002lst:4.x" - It's recommended to create topic branches for PRs.

[bit1002lst]

Sorry, there is a new PR.
#3351
and I will close this one

"opencv:4.x from bit1002lst:4.x" - It's recommended to create topic branches for PRs.