OPCUA-3371 Refactor subscriber method to simplify CAN frame reading logic

[luismiguensfernandez]

CLang detected a code-smell:

scan-build: Analysis run complete.
scan-build: Analysis results (plist files) deposited in '/builds/quasar-team/CanModule/build-clang/scan-build-reports/2026-06-07-235511-3040-1'
SCAN_PROJECT_COUNT=0
[clang-analysis] Running clang-tidy
Suppressed 1 warnings (1 NOLINT).
1 warning generated.
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:392:11: error: Out of bound access to memory after the end of 'events' [clang-analyzer-security.ArrayBound,-warnings-as-errors]
  392 |       if (events[i].data.fd == m_socket_fd) {
      |           ^~~~~~~~~
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:377:3: note: Loop condition is true.  Entering loop body
  377 |   while (m_subcriber_run) {
      |   ^
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:379:9: note: Assuming 'nfds' is >= 0
  379 |     if (nfds < 0) {
      |         ^~~~~~~~
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:379:5: note: Taking false branch
  379 |     if (nfds < 0) {
      |     ^
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:391:21: note: Assuming 'i' is < 'nfds'
  391 |     for (int i = 0; i < nfds; ++i) {
      |                     ^~~~~~~~
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:391:5: note: Loop condition is true.  Entering loop body
  391 |     for (int i = 0; i < nfds; ++i) {
      |     ^
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:392:11: note: Assuming field 'fd' is not equal to field 'm_socket_fd'
  392 |       if (events[i].data.fd == m_socket_fd) {
      |           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:392:7: note: Taking false branch
  392 |       if (events[i].data.fd == m_socket_fd) {
      |       ^
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:391:21: note: Assuming 'i' is < 'nfds'
  391 |     for (int i = 0; i < nfds; ++i) {
      |                     ^~~~~~~~
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:391:5: note: Loop condition is true.  Entering loop body
  391 |     for (int i = 0; i < nfds; ++i) {
      |     ^
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:392:11: note: Access of 'events' at index 1, while it holds only a single 'struct epoll_event' element
  392 |       if (events[i].data.fd == m_socket_fd) {
      |           ^~~~~~~~~
Suppressed 1 warnings (1 NOLINT).
1 warning treated as error
[clang-analysis] clang-tidy findings (project sources only):
/builds/quasar-team/CanModule/src/main/CanVendorSocketCan.cpp:392:11: error: Out of bound access to memory after the end of 'events' [clang-analyzer-security.ArrayBound,-warnings-as-errors]
[clang-analysis] ERROR: analyzer failures detected (scan-invocation-failed=0, scan-build-exit=0, scan-project-findings=0, clang-tidy=1)